Executive brief
wolfSSL is a security library used to protect communications for embedded devices and cloud services. A flaw in how it checks certificate revocation status (OCSP) could allow a certificate to be incorrectly reported as valid if its serial number starts with the same digits as a revoked certificate from the same issuer. This could lead to a system trusting a revoked or fraudulent certificate, potentially compromising secure connections.
Technical details
A length-confusion vulnerability exists in the `wolfSSL_OCSP_resp_find_status` function. The lookup logic compares serial number bytes without first verifying that the lengths of the two serial numbers are equal. Consequently, if a `SingleResponse` exists for a certificate (from the same issuer) whose serial number is a prefix of the target certificate's serial, the function returns a match. This allows the revocation status of one certificate to be incorrectly applied to another. An attacker could potentially leverage this to bypass certificate revocation checks. The issue is resolved by requiring an exact length match before byte comparison.
Affected products
- wolfSSL wolfSSL 4.6.0 through 5.9.1
Timeline
- 2026-05-29: other: Pull request submitted to wolfSSL repository
- 2026-06-04: patched: Fix merged into master branch
- 2026-06-25: disclosed: CVE published to NVD