CVE-2026-45659: Microsoft SharePoint Server Deserialization of Untrusted Data Vulnerability
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
Microsoft SharePoint Server contains a deserialization of untrusted data vulnerability which allows an authorized attacker to execute code over a network.
CSIRTS triage
- What
- A deserialization of untrusted data vulnerability allows code execution over a network.
- Who is affected
- Authorized users of Microsoft SharePoint Server are affected.
- Urgency
- Remediation is urgent due to active exploitation and critical severity.
- Action
- Apply the latest security patch for Microsoft SharePoint Server.
AI-assisted analysis generated from the source advisory — verify against the original.
⚡ Watch SharePoint Server
Get an email when a new SharePoint Server advisory drops — max one per day, one-click unsubscribe.
Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-45659
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Exploitation confirmedCVE-2026-45659Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 87% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-45659 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- criticalexploitedAL26-015 - Critical vulnerability impacting Microsoft SharePoint Server – CVE-2026-45659cccs
- high[UPDATE] [high] Microsoft SharePoint Server 2016 and SharePoint Server 2019: Vulnerability allows code executi…cert-bund
- highexploitedCISA Adds One Known Exploited Vulnerability to Catalogcisa
Recent advisories for Microsoft SharePoint Server
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- criticalexploitedAL26-015 - Critical vulnerability impacting Microsoft SharePoint Server – CVE-2026-45659cccs · 2026-07-02
- high[UPDATE] [high] Microsoft SharePoint Server 2016 and SharePoint Server 2019: Vulnerability allows code executi…cert-bund · 2026-07-02
- mediumCVE-2026-45479: Microsoft SharePoint Server Spoofing Vulnerabilitymsrc · 2026-06-09
- mediumCVE-2026-45468: Microsoft SharePoint Server Spoofing Vulnerabilitymsrc · 2026-06-09
- mediumCVE-2026-45467: Microsoft SharePoint Server Spoofing Vulnerabilitymsrc · 2026-06-09
- mediumCVE-2026-45453: Microsoft SharePoint Server Spoofing Vulnerabilitymsrc · 2026-06-09
More from CISA Known Exploited Vulnerabilities
- criticalCVE-2026-48939: iCagenda Unrestricted Upload of File with Dangerous Type Vulnerability2026-07-10
- criticalCVE-2026-56291: Balbooa Forms Unrestricted Upload of File with Dangerous Type Vulnerability2026-07-10
- criticalCVE-2026-48908: JoomShaper SP Page Builder Unrestricted Upload of File with Dangerous Type Vulnerability2026-07-07
- criticalCVE-2026-55255: Langflow Authorization Bypass Through User-Controlled Key Vulnerability2026-07-07
- criticalCVE-2026-48282: Adobe ColdFusion Path Traversal Vulnerability2026-07-07