Executive brief
wolfSSL is a cryptographic library used to secure TLS connections and certificate validation in applications. A flaw in the X509_verify_cert function allows an attacker to permanently inject an unverified certificate authority into the certificate manager, causing the library to accept fraudulent certificates in all subsequent validation checks. This could enable attackers to impersonate legitimate services or intercept encrypted communications.
Technical details
The vulnerability exists in wolfSSL's X509_verify_cert implementation when compiled with OpenSSL compatibility macros enabled. A failed certificate verification call stores an attacker-supplied CA in the shared CertManager without validation, and this poisoned state persists across all subsequent verification operations regardless of the consumer (TLS, OCSP, CRL, direct CM verify). The flaw affects versions 5.8.4 through 5.9.2 and requires the application to explicitly call X509_verify_cert with attacker-controlled input.
Affected products
- wolfSSL wolfSSL 5.8.4 through 5.9.2
Timeline
- 2026-09-27: disclosed
- 2026-08-11: patched