CVE-2025-53770: Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 20 Jul 2025, the same day the CVE record was published.
- How likely is exploitation in the next 30 days?
- 100%
EPSS score, percentile 100 of all scored records
- How severe?
- 9.8 Critical
CVSS v3.1 base score, given by the CNA
- What should I do?
Required action (CISA), due 21 Jul 2025: Disconnect 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.
- Which versions are affected?
Affected: 16.0.0 up to, not including, 16.0.5513.1001; 16.0.0 up to, not including, 16.0.10417.20037; 16.0.0 up to, not including, 16.0.18526.20508
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
Disconnect 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.
CISA due date for this action: 21 July 2025.
Advisories and patches
Linked from CISA's catalog entry
- https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770
- https://www.microsoft.com/en-us/security/blog/2025/07/22/disrupting-active-exploitation-of-on-premises-sharepoint-vulnerabilities/
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770
- https://nvd.nist.gov/vuln/detail/CVE-2025-53770
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 16.0.0 up to, not including, 16.0.5513.1001 |
| Status | Versions |
|---|---|
| Affected | 16.0.0 up to, not including, 16.0.10417.20037 |
| Status | Versions |
|---|---|
| Affected | 16.0.0 up to, not including, 16.0.18526.20508 |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this 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.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2025-53770 to its Known Exploited Vulnerabilities (KEV) catalog on 20 Jul 2025.
- CISA marks it as known to be used in ransomware campaigns.
- The due date CISA sets for the required action is 21 Jul 2025.
- The CVE record was published on 20 Jul 2025, the same day it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 9.8 (Critical), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 100% (percentile 100), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
Microsoft SharePoint Server Remote Code Execution Vulnerability
Deserialization of untrusted data in on-premises Microsoft SharePoint Server allows an unauthorized attacker to execute code over a network. Microsoft is aware that an exploit for CVE-2025-53770 exists in the wild. Microsoft is preparing and fully testing a comprehensive update to address this vulnerability. In the meantime, please make sure that the mitigation provided in this CVE documentation is in place so that you are protected from exploitation.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
- CWE-502: Deserialization of Untrusted Data
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 20 Jul 2025 | CVE record published |
| 20 Jul 2025 | Added to CISA KEV |
| 21 Jul 2025 | CISA due date for the required action |
| 4 Aug 2026 | CVE record last updated |
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