CVE-2026-82462

MEDIUM 6.5

pac4j-oidc before 6.5.6 Authentication Bypass via Access Token Substitution

CVSS Score

6.5

EPSS Score

0.0%

EPSS Percentile

0th

pac4j-oidc before 6.5.6 accepts OIDC callbacks carrying only an access token without authorization code or ID token validation. Attackers can substitute access tokens minted for other clients to create authenticated sessions without proper issuer, audience, nonce, or subject verification.

CWE	CWE-345
Vendor	pac4j
Product	pac4j
Published	Aug 29, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Affected Versions

pac4j / pac4j

0 < 6.5.6

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/pac4j/pac4j/commit/2270c3ff70e93cc43831e75702acd5135531237e pac4j.org: https://www.pac4j.org/blog/security-advisory-pac4j-core-oidc-saml.html github.com: https://github.com/pac4j/pac4j/blob/pac4j-parent-6.5.5/pac4j-oidc/src/main/java/org/pac4j/oidc/credentials/extractor/OidcCredentialsExtractor.java github.com: https://github.com/pac4j/pac4j vulncheck.com: https://www.vulncheck.com/advisories/pac4j-oidc-before-6.5.6-authentication-bypass-via-access-token-substitution

Credits

Joshua Rogers (AISLE Research)