CVE Catalog

CVE-2026-75759

HighCVSS 7.6
Published: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.14%

3th percentile - higher than 3% of all known CVEs

Summary

The oidcc library (erlef) has an improper verification of cryptographic signature vulnerability. An unauthenticated attacker can impersonate an arbitrary user via an encrypted ID token or JARM response carrying no nested signature. The library accepts a JWE wrapping unsigned claims as fully validated, allowing minting tokens with arbitrary sub, iss, and aud without the provider's signing key.

Risk Assessment

An attacker can gain access to user accounts in systems using OpenID Connect, leading to confidentiality and integrity breaches. The vulnerability affects versions from 3.2.0-beta.1 before 3.9.0.

Recommendation

Update the oidcc library to version 3.9.0 or later, which includes the fix. Check for any compromised tokens.

Related vulnerabilities

Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS