CVE-2026-55040: exploitation status and patch state

CVE-2026-55040 · CVSS 9.1 CRITICAL · patch available

Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.

Is CVE-2026-55040 exploited?

• Not in the CISA KEV catalog.
• Public exploit code: none found in monitored sources.

Which products and versions are affected?

No affected package list recorded here yet.

Is there a patch?

• KB5002891
• KB5002883
• KB5002882

What PlainSec published about CVE-2026-55040

• SharePoint JWT Flaw Is Being Exploited (2026-08-14)

Primary sources

• NVD record
• Microsoft KB5002891
• Microsoft KB5002883
• Microsoft KB5002882

What this record does not say

• No EPSS score.
• No affected package data.

KEV and EPSS are re-checked daily. Record last updated 2026-08-14.