SB2026061006 - Multiple vulnerabilities in Microsoft SharePoint

Description

This security bulletin contains information about 2 vulnerabilities.

1) Deserialization of Untrusted Data (CVE-ID: CVE-2026-45484)

CWE-ID: CWE-502 - Deserialization of Untrusted Data

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

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.

2) Path traversal (CVE-ID: CVE-2026-45454)

CWE-ID: CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to perform directory traversal attacks.

The vulnerability exists due to input validation error when processing directory traversal sequences in Microsoft SharePoint. A remote user can send a specially crafted HTTP request and read arbitrary files on the system.

Remediation

Install update from vendor's website.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45484
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45454