CVE-2026-5501 Improper Certificate Signature Verification in X.509 Chain Validation Allows Forged Leaf Certificates

wolfSSLX509verifycert in the OpenSSL compatibility layer accepts a certificate chain in which the leaf's signature is not checked, if the attacker supplies an untrusted intermediate with Basic Constraints CA:FALSE that is legitimately signed by a trusted root. An attacker who obtains any leaf...

ANT-2026-K8YY7WWS · wolfSSL · improper-cert-validation

improper-cert-validation high CVE-2026-5501 Severity Claude high · Security research firm high · Maintainer - Discovered by Claude Mythos Preview SECURITY RESEARCH FIRM ANALYSIS Triage and disclosure were performed by Calif. The writeup below is the document the firm sent to the maintainer...

UBUNTU-CVE-2021-4044

Internally libssl in OpenSSL calls X509verifycert on the client side to verify a certificate supplied by a server. That function may return a negative return value to indicate an internal error for example out of memory. Such a negative return value is mishandled by OpenSSL and will cause an IO...