CVE-2026-45659
Confirmed PUBLISHEDMicrosoft SharePoint Remote Code Execution Vulnerability
Recommended Action
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
At a Glance
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
- CVE Published
- May 22, 2026
- Exploitation Reported
- Jul 01, 2026
- CVSS
- 8.8 High
- EPSS
- 2.8%
Affected Versions
| Vendor | Product | Version | Status | Source |
|---|---|---|---|---|
| Microsoft |
Microsoft SharePoint Enterprise Server 2016
|
16.0.0 to < 16.0.5552.1002 |
Affected | CNA |
| Microsoft |
Microsoft SharePoint Server 2019
|
16.0.0 to < 16.0.10417.20128 |
Affected | CNA |
| Microsoft |
Microsoft SharePoint Server Subscription Edition
|
16.0.0 to < 16.0.19725.20280 |
Affected | CNA |
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 | 2026-07-01 19:00 UTC |
| CVE | 2026-07-01 20:31 UTC |
| All CISA Advisories | 2026-07-01 21:20 UTC |
No detection artifacts or sensor request patterns are available for this CVE yet.
Check back as sensor telemetry and scanner integrations are updated.
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 via the Pro API.
Learn About Virtual PatchesCVSS Scores
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Exploitation Status
Exploited in the wild
Recorded 2026-07-01 19:00:06 UTC · CISA
Proof of concept available
Recorded 2026-06-09 11:16:39 UTC · GitHub
Weaknesses (CWE)
-
Deserialization of Untrusted Data
Recent Mentions
All CISA Advisories · Jul 01, 2026
CISA has added one new vulnerability to its Known Exploited Vulnerabilities (KEV) Catalog, based on evidence of active exploitation. CVE-2026-45659 Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability This type of vulnerability is a frequent attack vector for malicious cyber actors and poses significant risks to the federal enterprise. Binding Operational Directive (BOD) 26-04: Prioritizing Security Updates Based on Risk establishes vulnerability management requirements for Federal Civilian Executive Branch (FCEB) agencies. BOD 26-04 reinforces the importance of the KEV Catalog and requires federal agencies to prioritize rapid remediation of high-risk vulnerabilities, specifically those identified by Common Vulnerabilities and Exposures (CVEs) listed in CISA’s KEV Catalog on publicly exposed assets that grant total control of the asset post-exploitation, while deferring action for lower-risk vulnerabilities. BOD 26-04 further establishes basic expectations for when agencies must check whether threat actors compromised the system before the patch was applied. While BOD 26-04 applies only to FCEB agencies, CISA encourages all organizations to adopt risk-based vulnerability management and prioritize remediation of KEV Catalog vulnerabilities. CISA will continue to add vulnerabilities to the catalog that meet the specified criteria. Aware of an exploited vulnerability not currently listed in the KEV Catalog? Submit it for potential addition through CISA’s KEV Nomination Form. Potential KEV additions must have a CVE ID, evidence of exploitation, and clear mitigation guidance.
TheHackerNews · May 26, 2026
Microsoft has rolled out updates to fix a remote code execution vulnerability impacting SharePoint that could be exploited by bad actors in attacks without requiring any specialized conditions to be met. The vulnerability, tracked as CVE-2026-45659, carries a CVSS score of 8.8. It has been assigned an important severity. "Deserialization of untrusted data in Microsoft Office SharePoint allows
Potential Proof of Concepts
These PoCs are unverified and could contain malware. Use at your own risk.
github · Created 2026-06-09 11:16:39 UTC · 0 stars
github · Created 2026-05-27 14:12:48 UTC · 0 stars
CVE-2026-45659 Microsoft SharePoint Server Deserialization RCE.
Timeline
Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.
-
21:20 UTC about 6 hours ago21:20 UTC · about 6 hours ago
KEV confirmed by All CISA Advisories
Exploitation attested by an external source
-
20:31 UTC about 7 hours ago20:31 UTC · about 7 hours ago
KEV confirmed by CVE
Exploitation attested by an external source
-
19:00 UTC about 8 hours ago19:00 UTC · about 8 hours ago
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
11:16 UTC 23 days ago11:16 UTC · 23 days ago
Public PoC available
Public proof-of-concept code published
-
22:04 UTC about 1 month ago22:04 UTC · about 1 month ago
CVE published
Vulnerability disclosed publicly
-
20:33 UTC about 2 months ago20:33 UTC · about 2 months 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-2026-45659
{
"cve_id": "CVE-2026-45659",
"title": "Microsoft SharePoint Remote Code Execution Vulnerability",
"affected_vendor": "Microsoft",
"affected_product": "Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, Microsoft SharePoint Server Subscription Edition",
"affected_versions": [
{ "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
],
"confidence": "Confirmed",
"cvss_score": 8.8,
"epss_score": 0.02781,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "...": "Pro API fields" },
"proof_of_concepts": [ "..." ],
"scanner_integrations": [ "..." ]
}