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Vulnerability record · CVE-2026-82461 · published 29 August 2026

CVE-2026-82461: Improper verification of cryptographic signature vulnerability

pac4j-oidc before 6.5.6 fails to verify access token signatures, issuers, audiences, or expiry when extracting Keycloak realm and client roles. Attackers can forge access tokens with administrative roles paired with valid ID tokens to bypass authorization checks in applications relying on pac4j role validation.

8.6 CVSS 4.0 High EPSS 0.32% · top 78.0% CWE-347 · Improper verification of cryptographic signature Awaiting Analysis
8.6CVSS 4.0 base score
0.32%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
5References
10 Sep 2026Last modified by NVD

Description

pac4j-oidc before 6.5.6 fails to verify access token signatures, issuers, audiences, or expiry when extracting Keycloak realm and client roles. Attackers can forge access tokens with administrative roles paired with valid ID tokens to bypass authorization checks in applications relying on pac4j role validation.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/pac4j/pac4j
https://github.com/pac4j/pac4j/blob/pac4j-parent-6.5.5/pac4j-oidc/src/main/java/org/pac4j/oidc/authorization/generator/K
https://github.com/pac4j/pac4j/commit/2270c3ff70e93cc43831e75702acd5135531237e
https://www.pac4j.org/blog/security-advisory-pac4j-core-oidc-saml.html
https://www.vulncheck.com/advisories/pac4j-oidc-before-6.5.6-privilege-escalation-via-unverified-keycloak-access-token

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-82461), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.