Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
Microsoft SharePoint Server on-premises contains a deserialization of untrusted data vulnerability that could allow an unauthorized attacker to execute code over a network. This vulnerability could be chained with CVE-2025-53771. CVE-2025-53770 is a patch bypass for CVE-2025-49704, and the updates for CVE-2025-53770 include more robust protection than those for CVE-2025-49704.
- Vendor
- Microsoft
- Product
- SharePoint
- CVSS
- 9.8
- EPSS (exploit probability)
- 100.0%
- Status
- kevransomware use
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2025-53770 being exploited?
Yes. CISA added CVE-2025-53770 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild. It is also listed in ENISA's EU Vulnerability Database (EUVD) exploited list and CIRCL's KEV catalog. CISA marks it as known to be used in ransomware campaigns.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 100.0% (scored October 14, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ LISTED ]
- CIRCL KEV[ LISTED ]
Catalog snapshot 2026-11-13. Full cross-catalog view: /kev-comparison
CVE-2025-53770 timeline
- Added to CIRCL KEVsame day as NVD
- Added to CISA KEVsame day as NVD
- Added to EU KEV (ENISA)same day as NVD
- Published to NVD
Every event links to its source. Catalog dates are each catalog's own; day offsets count from NVD publication. Data: JSON
What to do
CISA required actionDisconnect public-facing versions of SharePoint Server that have reached their end-of-life (EOL) or end-of-service (EOS) to include SharePoint Server 2013 and earlier versions. For supported versions, please follow the mitigations according to CISA (URL listed below in Notes) and vendor instructions (URL listed below in Notes). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.
US federal civilian agencies must remediate by (1 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Microsoft SharePoint CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2026-65660 Microsoft SharePoint Code Injection Vulnerabilitywrite-up | [ HIGH ] | 8.8 | 9.9% | |
| CVE-2026-55040 SharePoint Server JWT token authentication bypasswrite-up | [ CRITICAL ] | 9.1 | 69.5% | |
| CVE-2026-50522 SharePoint Server deserialization of untrusted data RCEwrite-up | [ CRITICAL ] | 9.8 | 3.0% | |
| CVE-2026-58644 Microsoft SharePoint deserialization of untrusted data (unauth RCE)write-up | [ CRITICAL ] | 9.8 | 15.9% | |
| CVE-2026-56164 SharePoint Server elevation of privilege — missing authentication for critical functionwrite-up | [ MEDIUM ] | 5.3 | 27.3% | |
| CVE-2026-45659 Microsoft SharePoint Server deserialization remote code executionransomware usewrite-up | [ HIGH ] | 8.8 | 80.2% | |
| CVE-2026-32201 SharePoint Server spoofing via improper input validationwrite-up | [ MEDIUM ] | 6.5 | 44.0% | |
| CVE-2026-20963 Microsoft SharePoint Deserialization of Untrusted Data Vulnerability | [ CRITICAL ] | 9.8 | 29.2% |