What is CVE-2026-83711?

CVE-2026-83711 is a critical-severity vulnerability in Microsoft Azure Active Directory B2c, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 10.0/10. Published 2026-09-03.

How severe is CVE-2026-83711?

Critical severity. CVSS v3 base score is 10.0 out of 10.

Auth bypass in Microsoft Azure Active Directory B2c

CVE-2026-83711

Authorization bypass through user-controlled key in Microsoft Azure Active Directory B2C allows an unauthorized attacker to elevate privileges over a network.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published 2026-09-03 · last modified 2026-10-14.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.008 (55.7th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 55.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.008 · change: +0.002

Affected products

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83711 (vendor-advisory, Patch, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-83711?: CVE-2026-83711 is a critical-severity vulnerability in Microsoft Azure Active Directory B2c, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 10.0/10. Published 2026-09-03.
How severe is CVE-2026-83711?: Critical severity. CVSS v3 base score is 10.0 out of 10.