CVE-2026-50522
Microsoft SharePoint Deserialization of Untrusted Data Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 25 July 2026). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 85.40% probability · 100th percentile
- CISA KEV
- Listed 22 July 2026 · due 25 July 2026
- Weakness
- CWE-502
- Affected
- microsoft/sharepoint server
- Source
- secure@microsoft.com
CISA notes
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50522 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-50522
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50522Patch, Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-50522US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.