CVE-2023-44487

Confirmed PUBLISHED

The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as...

Google · Cloud Platform

Exploited in the wild PoC available

Recommended Action

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

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Confidence

Confirmed

Exploitation Status

Exploited in the wild

Observed in Sensors

Attempts (30d)

—

Unique Attacker IPs

—

CISA KEV

In CISA KEV

CVSS / EPSS

7.5 High EPSS 100.0%

At a Glance

The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.

cisa nessus_scanner

CVE Published: Oct 10, 2023
Exploitation Reported: Oct 10, 2023
CVSS: 7.5 High
EPSS: 100.0%

Remote Low complexity No user interaction Unauthenticated

Affected Versions

Vendor	Product	Version	Status
ietf	http	2.0	Affected
Siemens	RUGGEDCOM APE1808	0 to < *	Affected
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP	V3.1.5 to < *	Affected
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP	V3.1.5 to < *	Affected
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP	V3.1.5 to < *	Affected
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP	V3.1.5 to < *	Affected
Siemens	SINEC NMS	0 to < V3.0	Affected
Siemens	SIPLUS S7-1500 CPU 1518-4 PN/DP MFP	V3.1.5 to < *	Affected
n/a	n/a	n/a	Affected

CVE References

DSA-5522 debian.org · Vendor Advisory https://www.debian.org/security/2023/dsa-5522
DSA-5521 debian.org · Vendor Advisory https://www.debian.org/security/2023/dsa-5521
FEDORA-2023-ed2642fd58 lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-54fadada12 lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-5ff7bf1dd8 lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....

Show 139 more references

FEDORA-2023-17efd3f2cd lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-d5030c983c lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-0259c3f26f lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-2a9214af5f lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-e9c04d81c1 lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-f66fc0f62a lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-4d2fd884ea lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-b2c50535cb lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-fe53e13b5b lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-4bf641255e lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
DSA-5540 debian.org · Vendor Advisory https://www.debian.org/security/2023/dsa-5540
FEDORA-2023-1caffb88af lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-3f70b8d406 lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-7b52921cae lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-7934802344 lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-dbe64661af lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-822aab0a5a lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
DSA-5549 debian.org · Vendor Advisory https://www.debian.org/security/2023/dsa-5549
FEDORA-2023-c0c6a91330 lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
FEDORA-2023-492b7be466 lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce@lists....
DSA-5558 debian.org · Vendor Advisory https://www.debian.org/security/2023/dsa-5558
GLSA-202311-09 security.gentoo.org · Vendor Advisory https://security.gentoo.org/glsa/202311-09
DSA-5570 debian.org · Vendor Advisory https://www.debian.org/security/2023/dsa-5570
[oss-security] 20231010 Re: CVE-2023-44487: HTTP/2 Rapid Reset attack against many implementations openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2023/10/10/7
[oss-security] 20231010 CVE-2023-44487: HTTP/2 Rapid Reset attack against many implementations openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2023/10/10/6
[debian-lts-announce] 20231013 [SECURITY] [DLA 3617-1] tomcat9 security update lists.debian.org · Mailing List https://lists.debian.org/debian-lts-announce/2023/10/msg00020.html
[oss-security] 20231013 Re: CVE-2023-44487: HTTP/2 Rapid Reset attack against many implementations openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2023/10/13/4
[oss-security] 20231013 Re: CVE-2023-44487: HTTP/2 Rapid Reset attack against many implementations openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2023/10/13/9
[debian-lts-announce] 20231016 [SECURITY] [DLA 3621-1] nghttp2 security update lists.debian.org · Mailing List https://lists.debian.org/debian-lts-announce/2023/10/msg00023.html
[debian-lts-announce] 20231016 [SECURITY] [DLA 3617-2] tomcat9 regression update lists.debian.org · Mailing List https://lists.debian.org/debian-lts-announce/2023/10/msg00024.html
[oss-security] 20231018 Vulnerability in Jenkins openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2023/10/18/4
[oss-security] 20231018 Re: CVE-2023-44487: HTTP/2 Rapid Reset attack against many implementations openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2023/10/18/8
[oss-security] 20231019 CVE-2023-45802: Apache HTTP Server: HTTP/2 stream memory not reclaimed right away on RST openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2023/10/19/6
[oss-security] 20231020 Re: CVE-2023-44487: HTTP/2 Rapid Reset attack against many implementations openwall.com · Mailing List http://www.openwall.com/lists/oss-security/2023/10/20/8
[debian-lts-announce] 20231030 [SECURITY] [DLA 3641-1] jetty9 security update lists.debian.org · Mailing List https://lists.debian.org/debian-lts-announce/2023/10/msg00045.html
[debian-lts-announce] 20231031 [SECURITY] [DLA 3638-1] h2o security update lists.debian.org · Mailing List https://lists.debian.org/debian-lts-announce/2023/10/msg00047.html
[debian-lts-announce] 20231105 [SECURITY] [DLA 3645-1] trafficserver security update lists.debian.org · Mailing List https://lists.debian.org/debian-lts-announce/2023/11/msg00001.html
[debian-lts-announce] 20231119 [SECURITY] [DLA 3656-1] netty security update lists.debian.org · Mailing List https://lists.debian.org/debian-lts-announce/2023/11/msg00012.html
GitHub — dotnet/core github.com · CVE Record https://github.com/dotnet/core/blob/e4613450ea0da7fd2fc6b61dfb2c1c1de...
blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-a... blog.cloudflare.com · CVE Record https://blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddo...
aws.amazon.com/security/security-bulletins/AWS-2023-011 aws.amazon.com · CVE Record https://aws.amazon.com/security/security-bulletins/AWS-2023-011/
cloud.google.com/blog/products/identity-security/how-it-works... cloud.google.com · CVE Record https://cloud.google.com/blog/products/identity-security/how-it-works...
nginx.com/blog/http-2-rapid-reset-attack-impacting-f5-... nginx.com · CVE Record https://www.nginx.com/blog/http-2-rapid-reset-attack-impacting-f5-ngi...
cloud.google.com/blog/products/identity-security/google-cloud... cloud.google.com · CVE Record https://cloud.google.com/blog/products/identity-security/google-cloud...
news.ycombinator.com/item news.ycombinator.com · CVE Record https://news.ycombinator.com/item?id=37831062
blog.cloudflare.com/zero-day-rapid-reset-http2-record-breaking-d... blog.cloudflare.com · CVE Record https://blog.cloudflare.com/zero-day-rapid-reset-http2-record-breakin...
phoronix.com/news/HTTP2-Rapid-Reset-Attack phoronix.com · CVE Record https://www.phoronix.com/news/HTTP2-Rapid-Reset-Attack
GitHub — envoyproxy/envoy github.com · CVE Record https://github.com/envoyproxy/envoy/pull/30055
GitHub — haproxy/haproxy github.com · CVE Record https://github.com/haproxy/haproxy/issues/2312
GitHub — eclipse/jetty.project github.com · CVE Record https://github.com/eclipse/jetty.project/issues/10679
forums.swift.org/t/swift-nio-http2-security-update-cve-2023-4... forums.swift.org · CVE Record https://forums.swift.org/t/swift-nio-http2-security-update-cve-2023-4...
GitHub — nghttp2/nghttp2 github.com · CVE Record https://github.com/nghttp2/nghttp2/pull/1961
GitHub — netty/netty github.com · CVE Record https://github.com/netty/netty/commit/58f75f665aa81a8cbcf6ffa74820042...
GitHub — alibaba/tengine github.com · CVE Record https://github.com/alibaba/tengine/issues/1872
GitHub — apache/tomcat github.com · CVE Record https://github.com/apache/tomcat/tree/main/java/org/apache/coyote/http2
news.ycombinator.com/item news.ycombinator.com · CVE Record https://news.ycombinator.com/item?id=37830987
news.ycombinator.com/item news.ycombinator.com · CVE Record https://news.ycombinator.com/item?id=37830998
GitHub — caddyserver/caddy github.com · CVE Record https://github.com/caddyserver/caddy/issues/5877
bleepingcomputer.com/news/security/new-http-2-rapid-reset-zero-da... bleepingcomputer.com · CVE Record https://www.bleepingcomputer.com/news/security/new-http-2-rapid-reset...
GitHub — bcdannyboy/CVE-2023-44487 github.com · CVE Record https://github.com/bcdannyboy/CVE-2023-44487
GitHub — grpc/grpc-go github.com · CVE Record https://github.com/grpc/grpc-go/pull/6703
GitHub — icing/mod_h2 github.com · CVE Record https://github.com/icing/mod_h2/blob/0a864782af0a942aa2ad4ed960a6b32c...
GitHub — nghttp2/nghttp2 github.com · CVE Record https://github.com/nghttp2/nghttp2/releases/tag/v1.57.0
mailman.nginx.org/pipermail/nginx-devel/2023-October/S36Q5HBXR... mailman.nginx.org · CVE Record https://mailman.nginx.org/pipermail/nginx-devel/2023-October/S36Q5HBX...
my.f5.com/manage/s/article/K000137106 my.f5.com · CVE Record https://my.f5.com/manage/s/article/K000137106
msrc.microsoft.com/blog/2023/10/microsoft-response-to-distribut... msrc.microsoft.com · CVE Record https://msrc.microsoft.com/blog/2023/10/microsoft-response-to-distrib...
bugzilla.proxmox.com/show_bug.cgi bugzilla.proxmox.com · CVE Record https://bugzilla.proxmox.com/show_bug.cgi?id=4988
cgit.freebsd.org/ports/commit cgit.freebsd.org · CVE Record https://cgit.freebsd.org/ports/commit/?id=c64c329c2c1752f46b73e3e6ce9...
seanmonstar.com/post/730794151136935936/hyper-http2-rapid-re... seanmonstar.com · CVE Record https://seanmonstar.com/post/730794151136935936/hyper-http2-rapid-res...
GitHub — microsoft/CBL-Mariner github.com · CVE Record https://github.com/microsoft/CBL-Mariner/pull/6381
groups.google.com/g/golang-announce/c/iNNxDTCjZvo groups.google.com · CVE Record https://groups.google.com/g/golang-announce/c/iNNxDTCjZvo
GitHub — facebook/proxygen github.com · CVE Record https://github.com/facebook/proxygen/pull/466
gist.github.com/adulau/7c2bfb8e9cdbe4b35a5e131c66a0c088 gist.github.com · CVE Record https://gist.github.com/adulau/7c2bfb8e9cdbe4b35a5e131c66a0c088
GitHub — micrictor/http2-rst-stream github.com · CVE Record https://github.com/micrictor/http2-rst-stream
edg.io/lp/blog/resets-leaks-ddos-and-the-tale-of-a-... edg.io · CVE Record https://edg.io/lp/blog/resets-leaks-ddos-and-the-tale-of-a-hidden-cve
openssf.org/blog/2023/10/10/http-2-rapid-reset-vulnerabi... openssf.org · CVE Record https://openssf.org/blog/2023/10/10/http-2-rapid-reset-vulnerability-...
GitHub — h2o/h2o github.com · CVE Record https://github.com/h2o/h2o/security/advisories/GHSA-2m7v-gc89-fjqf
GitHub — h2o/h2o github.com · CVE Record https://github.com/h2o/h2o/pull/3291
GitHub — nodejs/node github.com · CVE Record https://github.com/nodejs/node/pull/50121
GitHub — dotnet/announcements github.com · CVE Record https://github.com/dotnet/announcements/issues/277
GitHub — golang/go github.com · CVE Record https://github.com/golang/go/issues/63417
GitHub — advisories/GHSA-vx74-f528-fxqg github.com · CVE Record https://github.com/advisories/GHSA-vx74-f528-fxqg
GitHub — apache/trafficserver github.com · CVE Record https://github.com/apache/trafficserver/pull/10564
msrc.microsoft.com/update-guide/vulnerability/CVE-2023-44487 msrc.microsoft.com · CVE Record https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-44487
tomcat.apache.org/security-10.html tomcat.apache.org · CVE Record https://tomcat.apache.org/security-10.html#Fixed_in_Apache_Tomcat_10....
Apache Mailing List lists.apache.org · CVE Record https://lists.apache.org/thread/5py8h42mxfsn8l1wy6o41xwhsjlsd87q
OSS-Security Mailing List openwall.com · CVE Record https://www.openwall.com/lists/oss-security/2023/10/10/6
haproxy.com/blog/haproxy-is-not-affected-by-the-http-2-r... haproxy.com · CVE Record https://www.haproxy.com/blog/haproxy-is-not-affected-by-the-http-2-ra...
GitHub — opensearch-project/data-prepper github.com · CVE Record https://github.com/opensearch-project/data-prepper/issues/3474
GitHub — kubernetes/kubernetes github.com · CVE Record https://github.com/kubernetes/kubernetes/pull/121120
GitHub — oqtane/oqtane.framework github.com · CVE Record https://github.com/oqtane/oqtane.framework/discussions/3367
GitHub — advisories/GHSA-xpw8-rcwv-8f8p github.com · CVE Record https://github.com/advisories/GHSA-xpw8-rcwv-8f8p
netty.io/news/2023/10/10/4-1-100-Final.html netty.io · CVE Record https://netty.io/news/2023/10/10/4-1-100-Final.html
cisa.gov/news-events/alerts/2023/10/10/http2-rapid-re... cisa.gov · CVE Record https://www.cisa.gov/news-events/alerts/2023/10/10/http2-rapid-reset-...
theregister.com/2023/10/10/http2_rapid_reset_zeroday theregister.com · CVE Record https://www.theregister.com/2023/10/10/http2_rapid_reset_zeroday/
blog.qualys.com/vulnerabilities-threat-research/2023/10/10/c... blog.qualys.com · CVE Record https://blog.qualys.com/vulnerabilities-threat-research/2023/10/10/cv...
news.ycombinator.com/item news.ycombinator.com · CVE Record https://news.ycombinator.com/item?id=37837043
GitHub — kazu-yamamoto/http2 github.com · CVE Record https://github.com/kazu-yamamoto/http2/issues/93
martinthomson.github.io/h2-stream-limits/draft-thomson-httpbis-h2-st... martinthomson.github.io · CVE Record https://martinthomson.github.io/h2-stream-limits/draft-thomson-httpbi...
GitHub — kazu-yamamoto/http2 github.com · CVE Record https://github.com/kazu-yamamoto/http2/commit/f61d41a502bd0f60eb24e1c...
GitHub — apache/httpd github.com · CVE Record https://github.com/apache/httpd/blob/afcdbeebbff4b0c50ea26cdd16e178c0...
access.redhat.com/security/cve/cve-2023-44487 access.redhat.com · CVE Record https://access.redhat.com/security/cve/cve-2023-44487
GitHub — ninenines/cowboy github.com · CVE Record https://github.com/ninenines/cowboy/issues/1615
GitHub — varnishcache/varnish-cache github.com · CVE Record https://github.com/varnishcache/varnish-cache/issues/3996
GitHub — tempesta-tech/tempesta github.com · CVE Record https://github.com/tempesta-tech/tempesta/issues/1986
blog.vespa.ai/cve-2023-44487 blog.vespa.ai · CVE Record https://blog.vespa.ai/cve-2023-44487/
GitHub — etcd-io/etcd github.com · CVE Record https://github.com/etcd-io/etcd/issues/16740
darkreading.com/cloud/internet-wide-zero-day-bug-fuels-large... darkreading.com · CVE Record https://www.darkreading.com/cloud/internet-wide-zero-day-bug-fuels-la...
istio.io/latest/news/security/istio-security-2023-004 istio.io · CVE Record https://istio.io/latest/news/security/istio-security-2023-004/
GitHub — junkurihara/rust-rpxy github.com · CVE Record https://github.com/junkurihara/rust-rpxy/issues/97
bugzilla.suse.com/show_bug.cgi bugzilla.suse.com · CVE Record https://bugzilla.suse.com/show_bug.cgi?id=1216123
bugzilla.redhat.com/show_bug.cgi bugzilla.redhat.com · CVE Record https://bugzilla.redhat.com/show_bug.cgi?id=2242803
ubuntu.com/security/CVE-2023-44487 ubuntu.com · CVE Record https://ubuntu.com/security/CVE-2023-44487
community.traefik.io/t/is-traefik-vulnerable-to-cve-2023-44487/20125 community.traefik.io · CVE Record https://community.traefik.io/t/is-traefik-vulnerable-to-cve-2023-4448...
GitHub — advisories/GHSA-qppj-fm5r-hxr3 github.com · CVE Record https://github.com/advisories/GHSA-qppj-fm5r-hxr3
GitHub — apache/httpd-site github.com · CVE Record https://github.com/apache/httpd-site/pull/10
GitHub — projectcontour/contour github.com · CVE Record https://github.com/projectcontour/contour/pull/5826
GitHub — linkerd/website github.com · CVE Record https://github.com/linkerd/website/pull/1695/commits/4b9c6836471bc827...
GitHub — line/armeria github.com · CVE Record https://github.com/line/armeria/pull/5232
blog.litespeedtech.com/2023/10/11/rapid-reset-http-2-vulnerablilty blog.litespeedtech.com · CVE Record https://blog.litespeedtech.com/2023/10/11/rapid-reset-http-2-vulnerab...
security.paloaltonetworks.com/CVE-2023-44487 security.paloaltonetworks.com · CVE Record https://security.paloaltonetworks.com/CVE-2023-44487
GitHub — akka/akka-http github.com · CVE Record https://github.com/akka/akka-http/issues/4323
GitHub — openresty/openresty github.com · CVE Record https://github.com/openresty/openresty/issues/930
GitHub — apache/apisix github.com · CVE Record https://github.com/apache/apisix/issues/10320
GitHub — Azure/AKS github.com · CVE Record https://github.com/Azure/AKS/issues/3947
GitHub — Kong/kong github.com · CVE Record https://github.com/Kong/kong/discussions/11741
GitHub — arkrwn/PoC github.com · CVE Record https://github.com/arkrwn/PoC/tree/main/CVE-2023-44487
netlify.com/blog/netlify-successfully-mitigates-cve-2023... netlify.com · CVE Record https://www.netlify.com/blog/netlify-successfully-mitigates-cve-2023-...
GitHub — caddyserver/caddy github.com · CVE Record https://github.com/caddyserver/caddy/releases/tag/v2.7.5
arstechnica.com/security/2023/10/how-ddosers-used-the-http-2... arstechnica.com · CVE Record https://arstechnica.com/security/2023/10/how-ddosers-used-the-http-2-...
lists.w3.org/Archives/Public/ietf-http-wg/2023OctDec/0025... lists.w3.org · CVE Record https://lists.w3.org/Archives/Public/ietf-http-wg/2023OctDec/0025.html
linkerd.io/2023/10/12/linkerd-cve-2023-44487 linkerd.io · CVE Record https://linkerd.io/2023/10/12/linkerd-cve-2023-44487/
security.netapp.com/advisory/ntap-20231016-0001 security.netapp.com · CVE Record https://security.netapp.com/advisory/ntap-20231016-0001/
discuss.hashicorp.com/t/hcsec-2023-32-vault-consul-and-boundary-af... discuss.hashicorp.com · CVE Record https://discuss.hashicorp.com/t/hcsec-2023-32-vault-consul-and-bounda...
security.netapp.com/advisory/ntap-20240426-0007 security.netapp.com · CVE Record https://security.netapp.com/advisory/ntap-20240426-0007/
security.netapp.com/advisory/ntap-20240621-0006 security.netapp.com · CVE Record https://security.netapp.com/advisory/ntap-20240621-0006/
security.netapp.com/advisory/ntap-20240621-0007 security.netapp.com · CVE Record https://security.netapp.com/advisory/ntap-20240621-0007/
GitHub — grpc/grpc github.com · CVE Record https://github.com/grpc/grpc/releases/tag/v1.59.2
sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisor... sec.cloudapps.cisco.com · CVE Record https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurity...

Recommended Actions

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Known Exploited Vulnerability Sources

Catalogues that list this CVE as a known exploited vulnerability.

Per-source evidence links for KEV attestations are available through the KEVIntel Pro API.

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Source	Added
CISA First	2023-10-10 00:00 UTC
CVE	2026-06-05 09:28 UTC

CVSS Scores

CVSS v3.1 7.5 High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation Status

Exploited in the wild

Recorded 2023-10-10 00:00:00 UTC · CISA

Proof of concept available

Recorded 2023-10-10 14:20:42 UTC · GitHub

Weaknesses (CWE)

CWE-400

Uncontrolled Resource Consumption

Scanner Integrations

Scanner	Reference	Detected
Nessus	https://www.tenable.com/plugins/nessus/237067	Jun 02, 2025

Recent Mentions

[io.netty:netty-codec-http2] Netty HTTP/2: Advertised MAX_CONCURRENT_STREAMS are not enforced

Github Advisory Database (Maven) · Jun 08, 2026

Impact DefaultHttp2Connection.DefaultEndpoint initialises maxActiveStreams/maxStreams to Integer.MAX_VALUE, and Http2Settings never inserts SETTINGS_MAX_CONCURRENT_STREAMS by default (Http2Settings.java:305-307 only clamps a user-supplied value). Unless the application explicitly calls initialSettings().maxConcurrentStreams(n), a Netty HTTP/2 server advertises no limit and enforces none locally. Each open stream allocates a DefaultStream object, PropertyMap slots, flow-controller state and IntObjectHashMap entry; with ~2^30 permissible odd stream IDs a single TCP connection can create hundreds of thousands of long-lived stream objects. This is also the precondition for CVE-2023-44487-style Rapid-Reset amplification, where the absence of a low concurrent cap multiplies backend work. Resources https://www.rfc-editor.org/rfc/rfc7540.html#section-6.5.2 References https://github.com/netty/netty/security/advisories/GHSA-5x3r-wrvg-rp6q https://github.com/netty/netty/releases/tag/netty-4.1.135.Final https://github.com/netty/netty/releases/tag/netty-4.2.15.Final https://github.com/advisories/GHSA-5x3r-wrvg-rp6q

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

threatlabindonesia/CVE-2023-44487-HTTP-2-Rapid-Reset-Exploit-PoC

github · Created 2024-12-03 14:54:21 UTC · 3 stars

ReToCode/golang-CVE-2023-44487

github · Created 2023-10-25 09:11:46 UTC · 2 stars

studiogangster/CVE-2023-44487

github · Created 2023-10-16 11:07:50 UTC · 19 stars

A python based exploit to test out rapid reset attack (CVE-2023-44487)

imabee101/CVE-2023-44487

github · Created 2023-10-11 01:59:47 UTC · 54 stars

Proof of concept for DoS exploit

bcdannyboy/CVE-2023-44487

github · Created 2023-10-10 14:20:42 UTC · 230 stars

Basic vulnerability scanning to see if web servers may be vulnerable to CVE-2023-44487

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GET /api/v2/pro/kevs/CVE-2023-44487

{
  "cve_id": "CVE-2023-44487",
  "title": "The HTTP/2 protocol allows a denial of service (server resource consumption) ...",
  "affected_vendor": "Google",
  "affected_product": "Cloud Platform",
  "affected_versions": [
    { "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
  ],
  "confidence": "Confirmed",
  "cvss_score": 7.5,
  "epss_score": 0.99999,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "...": "Pro API fields" },
  "proof_of_concepts": [ "..." ],
  "scanner_integrations": [ "..." ]
}

The free JSON API returns basic KEV fields only. Confidence, telemetry, and artifact enrichment require Pro API access.

CVE-2023-44487

At a Glance

Affected Versions

CVE References

Recommended Actions

Known Exploited Vulnerability Sources

Virtual Patch

CVSS Scores

Exploitation Status

Weaknesses (CWE)

Scanner Integrations

Recent Mentions

Potential Proof of Concepts

Timeline

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