CVE-2025-53770: Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

CISA Known Exploited Vulnerabilities

Name

Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

Vendor

Microsoft

Product

SharePoint

Added to the catalog

2025-07-20

Due date for US federal agencies

2025-07-21

Weaknesses

CWE-502

Catalog version

2026.10.30

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.

Required action (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.

Ransomware use: CISA marks this vulnerability as known to be used in ransomware campaigns. CISA does not say which group used it.

Links in CISA's notes

• 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

Read on 2026-11-02T23:39:54.475Z under licence cisa-kev-cc0@b0067899 from https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

NVD analysis

Status

Analyzed

Published

2025-07-20T01:15:30.777

Last modified

2026-08-04T05:16:34.887

Weaknesses

CWE-502

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.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770 (Vendor Advisory)
• https://arstechnica.com/security/2025/07/sharepoint-vulnerability-with-9-8-severity-rating-is-under-exploit-across-the-globe/ (Exploit, Press/Media Coverage)
• https://github.com/kaizensecurity/CVE-2025-53770 (Exploit)
• https://msrc.microsoft.com/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025-53770/ (Mitigation, Vendor Advisory)
• https://news.ycombinator.com/item?id=44629710 (Issue Tracking)
• https://research.eye.security/sharepoint-under-siege/ (Exploit, Mitigation, Third Party Advisory)
• https://therecord.media/microsoft-sharepoint-zero-day-vulnerability-exploited-globally (Press/Media Coverage)
• https://www.bleepingcomputer.com/news/microsoft/microsoft-sharepoint-zero-day-exploited-in-rce-attacks-no-patch-available/ (Press/Media Coverage)
• https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770 (Mailing List, Third Party Advisory, US Government Resource)
• https://www.darkreading.com/remote-workforce/microsoft-rushes-emergency-fix-exploited-sharepoint-toolshell-flaw (Press/Media Coverage)
• https://www.forbes.com/sites/daveywinder/2025/07/20/microsoft-confirms-ongoing-mass-sharepoint-attack---no-patch-available/ (Press/Media Coverage)
• https://x.com/Shadowserver/status/1946900837306868163 (Third Party Advisory)
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-53770 (US Government Resource)

This product uses the NVD API but is not endorsed or certified by the NVD.

Read on 2026-11-02T23:42:22.836Z under licence nvd-api-terms-of-use@ff2a5288 from https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2025-53770

CVE record

Title (CNA)

Microsoft SharePoint Server Remote Code Execution Vulnerability

Assigner

microsoft

State

PUBLISHED

Published

2025-07-20T01:06:33.607Z

Updated

2026-08-04T03:55:52.588Z

Problem types

CWE-502: Deserialization of Untrusted Data

References

• Microsoft SharePoint Server Remote Code Execution Vulnerability

Read on 2026-11-03T02:17:08.617Z under licence cve-terms-of-use@81bfa2f3 from https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2025/53xxx/CVE-2025-53770.json

Detection rules (SigmaHQ)

SigmaHQ rules whose own tags name this CVE. Each rule page shows the rule as its author published it.

• SharePoint ToolShell CVE-2025-53770 Exploitation - Web IIS (status experimental, level medium)
• Potential SharePoint ToolShell CVE-2025-53770 Exploitation Indicators (status experimental, level high)
• Potential SharePoint ToolShell CVE-2025-53770 Exploitation - File Create (status experimental, level critical)

Defensive techniques (MITRE D3FEND)

D3FEND maps these defensive techniques to the weakness (CWE) that NVD lists for this CVE, through the digital artifacts the weakness affects. D3FEND does not say they stop this vulnerability.

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