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CVE-2025-59245VulnerabilityPublished Updated

CVE-2025-59245: Microsoft SharePoint Online · Deserialization of Untrusted Data

Affects Microsoft SharePoint OnlineSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.1% chance of exploitation in 30 days – higher than 66% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 20 Nov 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

What to do

AI-suggested

Given the absence of an official patch at the time of disclosure, organizations should implement immediate compensating controls to reduce risk. These include: 1) Restricting network access to SharePoint Online administration interfaces to trusted IP addresses and enforcing strict access controls using conditional access policies in Azure AD. 2) Enabling multi-factor authentication (MFA) for all users, especially administrators, to reduce the risk of credential compromise. 3) Monitoring SharePoint Online logs and Microsoft 365 security alerts for unusual activities indicative of privilege escalation attempts. 4) Applying the principle of least privilege by reviewing and minimizing user permissions within SharePoint Online. 5) Utilizing Microsoft Defender for Office 365 and Microsoft Cloud App Security to detect and respond to suspicious behaviors. 6) Preparing for rapid deployment of security updates by maintaining an up-to-date inventory of affected assets and testing patching procedures. 7) Educating IT and security teams about the vulnerability specifics to ensure timely response. Once Microsoft releases a patch, organizations should prioritize its deployment to fully remediate the vulnerability.

Description

Microsoft SharePoint Online Elevation of Privilege Vulnerability

References

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