Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.
Exploitation probability EPSS · FIRST
Exploitation signals 4 / 5
- KEV catalog (CISA)18 Mar 2026
- Exploited in EUVD (ENISA)12 Mar 2026
- Used by ransomwareno
- EPSS above 10 %29.2%
- No account, over the networkyes
What to do
Fix
Apply the vendor’s fix as soon as it is available.
CISA guidance: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Meanwhile
Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.
Manufacturers (CRA)
Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained
Affected products
- 16.0.0 <16.0.10417.20083
- 16.0.0 <16.0.19127.20442
- 16.0.0 <16.0.5535.1001
Open source packages OSV
Affected libraries according to OSV, with fixed versions.
Timeline
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Published
-
Exploitation reported (ENISA)
-
Added to the KEV catalog
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CISA remediation due date
-
EPSS peak: 29.6%
References
Other exploited vulnerabilities from the same vendor
- CVE-2026-96951Microsoft Windows Command Injection Vulnerability5.6 · Actively exploited
- CVE-2026-65660Microsoft SharePoint Code Injection Vulnerability5.0 · Actively exploited
- CVE-2026-85880Microsoft Windows Heap-Based Buffer Overflow Vulnerability4.3 · Actively exploited
- CVE-2026-81963Microsoft Windows Link Following Vulnerability4.3 · Actively exploited
- CVE-2019-1068Microsoft SQL Server Remote Code Execution Vulnerability7.0 · Actively exploited
- CVE-2026-69836Microsoft Entra5.3 · Actively exploited