CVE-2021-39144
Confirmed PUBLISHEDXStream is vulnerable to a Remote Command Execution attack
Recommended Action
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
At a Glance
XStream is a simple library to serialize objects to XML and back again. In affected versions this vulnerability may allow a remote attacker has sufficient rights to execute commands of the host only by manipulating the processed input stream. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types. XStream 1.4.18 uses no longer a blacklist by default, since it cannot be secured for general purpose.
- CVE Published
- Aug 23, 2021
- Exploitation Reported
- Mar 10, 2023
- CVSS
- 8.5 High
- EPSS
- 98.1%
Affected Versions
| Vendor | Product | Version | Status |
|---|---|---|---|
| x-stream |
xstream
|
< 1.4.18 |
Affected |
CVE References
- FEDORA-2021-fbad11014a lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce%40list...
- FEDORA-2021-d894ca87dc lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce%40list...
- FEDORA-2021-5e376c0ed9 lists.fedoraproject.org · Vendor Advisory https://lists.fedoraproject.org/archives/list/package-announce%40list...
- DSA-5004 debian.org · Vendor Advisory https://www.debian.org/security/2021/dsa-5004
- [debian-lts-announce] 20210929 [SECURITY] [DLA 2769-1] libxstream-java security update lists.debian.org · Mailing List https://lists.debian.org/debian-lts-announce/2021/09/msg00017.html
Show 7 more references
- GitHub — x-stream/xstream github.com · CVE Record https://github.com/x-stream/xstream/security/advisories/GHSA-j9h8-phr...
- x-stream.github.io/CVE-2021-39144.html x-stream.github.io · CVE Record https://x-stream.github.io/CVE-2021-39144.html
- oracle.com/security-alerts/cpujan2022.html oracle.com · CVE Record https://www.oracle.com/security-alerts/cpujan2022.html
- security.netapp.com/advisory/ntap-20210923-0003 security.netapp.com · CVE Record https://security.netapp.com/advisory/ntap-20210923-0003/
- oracle.com/security-alerts/cpuapr2022.html oracle.com · CVE Record https://www.oracle.com/security-alerts/cpuapr2022.html
- oracle.com/security-alerts/cpujul2022.html oracle.com · CVE Record https://www.oracle.com/security-alerts/cpujul2022.html
- packetstormsecurity.com/files/169859/VMware-NSX-Manager-XStream-Unau... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/169859/VMware-NSX-Manager-XStrea...
Recommended Actions
- Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
- Check enrichment artifacts for scanner coverage and available PoCs before rolling remediation validation.
- Use the Pro API to automate enrichment, telemetry, and workflow delivery for VM, SOC, and CTI pipelines.
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.
Learn about Pro API access| Source | Added |
|---|---|
| CISA First | 2023-03-10 00:00 UTC |
| The Shadowserver | 2026-07-04 00:00 UTC |
Scanner Artifacts
Nuclei and Metasploit references linked to this CVE.
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-39144.yaml | Apr 25, 2025 |
| Metasploit | https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/http/vmware_nsxmgr_xstream_rce_cve_2021_39144.rb | Apr 28, 2025 |
Virtual Patch
Compensating WAF rules to help reduce exposure to this CVE. Rule content and deployable vendor exports are available with KEVIntel Enterprise.
KEVIntel does not currently have a virtual patch for this CVE. When available, KEVIntel virtual patches ship as deployable ModSecurity, Cloudflare, and AWS WAF rules.
Enterprise feature. Virtual patch rule content and deployable vendor exports (ModSecurity, Cloudflare, AWS WAF) are available to KEVIntel Enterprise users.
CVSS Scores
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
AV:N/AC:M/Au:S/C:P/I:P/A:P
Exploitation Status
Exploited in the wild
Recorded 2023-03-10 00:00:00 UTC · CISA
Proof of concept available
Recorded 2025-04-28 15:02:11 UTC · Nuclei Templates
Weaknesses (CWE)
-
Missing Authentication for Critical Function
-
Deserialization of Untrusted Data
-
Improper Control of Generation of Code ('Code Injection')
Scanner Integrations
| Scanner | Reference | Detected |
|---|---|---|
| Metasploit | https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/http/vmware_nsxmgr_xstream_rce_cve_2021_39144.rb | Apr 28, 2025 |
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-39144.yaml | Apr 25, 2025 |
Potential Proof of Concepts
These PoCs are unverified and could contain malware. Use at your own risk.
nuclei · Created Unknown
metasploit · Created Unknown
Metasploit module for CVE-2021-39144
Timeline
Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.
-
00:00 UTC 16 days ago00:00 UTC · 16 days ago
KEV confirmed by The Shadowserver
Exploitation attested by an external source
-
15:02 UTC about 1 year ago15:02 UTC · about 1 year ago
Metasploit module available
Exploit module available
-
15:02 UTC about 1 year ago15:02 UTC · about 1 year ago
Public PoC available
Public proof-of-concept code published
-
00:00 UTC about 1 year ago00:00 UTC · about 1 year ago
Nuclei template available
Scanner coverage available
-
00:00 UTC over 3 years ago00:00 UTC · over 3 years ago
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
00:00 UTC almost 5 years ago00:00 UTC · almost 5 years ago
CVE published
Vulnerability disclosed publicly
-
00:00 UTC almost 5 years ago00:00 UTC · almost 5 years ago
CVE ID reserved
Identifier reserved by the CNA
Automate This Intelligence with the Pro API
Confidence scoring, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
Pro API Example
GET /api/v2/pro/kevs/CVE-2021-39144
{
"cve_id": "CVE-2021-39144",
"title": "XStream is vulnerable to a Remote Command Execution attack",
"affected_vendor": "x-stream",
"affected_product": "xstream",
"affected_versions": [
{ "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
],
"confidence": "Confirmed",
"cvss_score": 8.5,
"epss_score": 0.98124,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "...": "Pro API fields" },
"proof_of_concepts": [ "..." ],
"scanner_integrations": [ "..." ]
}