What is CVE-2026-80098?

CVE-2026-80098 is a critical-severity vulnerability in Microsoft Copilot Studio, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.3/10. Published 2026-09-03.

How severe is CVE-2026-80098?

Critical severity. CVSS v3 base score is 9.3 out of 10.

Vulnerability in Microsoft Copilot Studio

CVE-2026-80098

Improper verification of cryptographic signature in Copilot Studio allows an unauthorized attacker to elevate privileges over a network.

Published 2026-09-03 · last modified 2026-09-08.

CVSS v3 metric

CVSS v3 base score 9.3 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N.

EPSS exploit prediction

EPSS: 0.005 (40.6th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 40.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002

Affected products

Weakness classification (CWE)

CWE-347 — Improper Verification of Cryptographic Signature

References

Copilot Studio Elevation of Privilege Vulnerability (vendor-advisory, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-80098?: CVE-2026-80098 is a critical-severity vulnerability in Microsoft Copilot Studio, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.3/10. Published 2026-09-03.
How severe is CVE-2026-80098?: Critical severity. CVSS v3 base score is 9.3 out of 10.