SB2026011474 - Multiple vulnerabilities in Microsoft SharePoint

Description

This security bulletin contains information about 2 secuirty vulnerabilities.

1) Server-Side Request Forgery (SSRF) (CVE-ID: CVE-2026-20958)

The disclosed vulnerability allows a remote attacker to perform SSRF attacks.

The vulnerability exists due to insufficient validation of user-supplied input in Microsoft SharePoint. A remote user can send a specially crafted HTTP request and trick the application to initiate requests to arbitrary systems.

Successful exploitation of this vulnerability may allow a remote attacker gain access to sensitive data, located in the local network or send malicious requests to other servers from the vulnerable system.

2) Deserialization of Untrusted Data (CVE-ID: CVE-2026-20963)

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to insecure input validation when processing serialized data in Microsoft SharePoint. A remote user can pass specially crafted data to the application and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Remediation

Install update from vendor's website.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20958
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20963