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CVE-2026-45069 – Authentication Bypass – Symfony 6.3–6.4.39, 7.4.0–7.4.11, 8.0.0–8.0.11

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Summary

CVE-2026-45069 is a high-severity authentication bypass vulnerability in Symfony’s OidcTokenHandler component, affecting the symfony/security-http package in versions ≥6.3 <6.4.40, ≥7.4 <7.4.12, and ≥8.0 <8.0.12. A logic flaw in claim verification allows a validly signed JWT that omits mandatory security claims to pass authentication, potentially granting an unauthenticated remote attacker unauthorized access to protected resources. The vulnerability carries a CVSS 4.0 score of 8.8 (High).

Technical details

  • Root cause: OidcTokenHandler::verifyClaims() registers checkers for the audience (aud), issuer (iss), and expiry (exp) JWT claims, but never passes the $mandatoryClaims argument to ClaimCheckerManager::check(). Because the underlying ClaimCheckerManager only validates claims that are actually present in the token, any registered checker for an absent claim is silently skipped.
  • Trigger condition: The vulnerability is exploitable only in Symfony applications that have configured OidcTokenHandler for OpenID Connect (OIDC) bearer token authentication — this is not a default Symfony configuration.
  • Attack vector: A remote, unauthenticated attacker presents a bearer JWT that is validly signed by a trusted Identity Provider (IdP) but has the aud, iss, and exp claims stripped. The token passes OidcTokenHandler verification without those critical claims being checked.
  • Impact: Authentication bypass — the attacker gains access as an authenticated user to any resource protected by the OidcTokenHandler mechanism, with high confidentiality impact (VC:H) and low integrity impact (VI:L) on the vulnerable system per the CVSS 4.0 assessment.
  • CWE: CWE-345 (Insufficient Verification of Data Authenticity); CWE-1287 (Improper Validation of Specified Type of Input).

Affected software

  • symfony/security-http and symfony/symfony ≥6.3, <6.4.40
  • symfony/security-http and symfony/symfony ≥7.4, <7.4.12
  • symfony/security-http and symfony/symfony ≥8.0, <8.0.12

Severity

CVSS 4.0 base score: 8.8 (High)
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

Mitigation and recommended actions

  • Immediate — upgrade to a patched release:
    • Symfony 6.x: upgrade to 6.4.40 or later
    • Symfony 7.x: upgrade to 7.4.12 or later
    • Symfony 8.x: upgrade to 8.0.12 or later
  • If immediate patching is not possible: Restrict external network access to OIDC-protected endpoints at the perimeter (WAF/firewall) to reduce exposure, and review Identity Provider logs for anomalous bearer token usage. Note that network-layer mitigations are not a substitute for patching.

IONIX Status

The IONIX research team is tracking ongoing exploitation attempts and recommends immediate patching. Potentially affected assets are outlined in this post.

References

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