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CVE-2026-75759: oidcc

Severity

7.6 (HIGH)

Vendor

ERLEF

Affected versions

3.2.0-beta.1 through before 3.9.0; 37a1361f704889816db2873f72d744d63ec39568 through before 5f62fbccdae8526ff62653b890165

Fixed version

3.9.0.

Patch status

Patched

Published

2026-08-30T02:18:30.110

Modified

2026-08-30T02:18:30.110

Why it matters

This matters because the issue affects identity or token handling. Successful exploitation could allow unauthorized authentication, client manipulation, or access to protected services.

Recommended admin actions

• Review and patch based on exposure, asset criticality, and business impact.
• Compare installed versions against the affected version range in the advisory.
• Treat internet-facing systems as higher priority.

Technical summary

Improper Verification of Cryptographic Signature vulnerability in erlef oidcc allows an unauthenticated attacker to impersonate an arbitrary user via an encrypted ID token or JARM response carrying no nested signature. OpenID Connect Core 1.0 section 2 requires that an encrypted ID token be signed then encrypted, with the result being a Nested JWT, and JARM processing rule 5 requires the client to check the signature unconditionally. oidcc instead accepted a JWE wrapping unsigned claims as fully validated, so anyone holding the relying party's public encryption key could mint a token with an arbitrary sub, iss, and aud without possessing the provider's signing key. In oidcc_jwt_util:verify_decrypted_token/4, a decrypted payload that is not a signed JWS fell back to parsing the plaintext claims and returning them with no verifying key. oidcc_token:int_validate_jwt/4 then matched on the JOSE structure type rather than on whether a signature had been verified, and returned success. The JARM path in oidcc_token:validate_jarm/3 is reachable through the browser front channel. UserInfo responses are not affected, because OpenID Connect Core 1.0 section 5.3.2 permits them to be encrypted without also being signed. This issue affects oidcc: from 3.2.0-beta.1 before 3.9.0.

View the official NVD record for CVE-2026-75759

CVE data is sourced from NVD/CNA records and optional enrichment. Validate against the vendor advisory before taking production action.