EUVD-2026-36765

In OCaml-TLS before 2.1.0, the server implementation does insufficient checks of the certificate provided by the client when doing client authentication, which allows impersonation with certificates that are not meant for client authentication because of KeyUsage and ExtendedKeyUsage...

CVE-2026-45388

In OCaml-TLS before 2.1.0, the client implementation does insufficient checks of the certificate provided by the server, which allows impersonation with certificates that are not meant for server authentication because of KeyUsage and ExtendedKeyUsage...

CVE-2026-45389

In OCaml-TLS before 2.1.0, the server implementation does insufficient checks of the certificate provided by the client when doing client authentication, which allows impersonation with certificates that are not meant for client authentication because of KeyUsage and ExtendedKeyUsage...

CVE-2026-45388

OCaml-TLS versions prior to 2.1.0 are vulnerable to a certificate validation flaw during TLS 1.3 handshakes. The client implementation fails to call the validate_keyusage function in handshake_client13.ml, meaning it does not verify the KeyUsage and ExtendedKeyUsage (EKU) extensions. Consequently...

CVE-2026-45389

In OCaml-TLS before 2.1.0, the server implementation does insufficient checks of the certificate provided by the client when doing client authentication, which allows impersonation with certificates that are not meant for client authentication because of KeyUsage and ExtendedKeyUsage...

CVE-2026-45389

OCaml-TLS versions prior to 2.1.0 are vulnerable to a security weakness where the server implementation fails to properly validate the KeyUsage and ExtendedKeyUsage extensions of client certificates during mutual TLS (mTLS) authentication. Specifically, the library does not verify if a certificat...

CVE-2026-45388: Improper Certificate Validation

In OCaml-TLS before 2.1.0, the client implementation does insufficient checks of the certificate provided by the server, which allows impersonation with certificates that are not meant for server authentication because of KeyUsage and ExtendedKeyUsage...

CVE-2026-45389

In OCaml-TLS before 2.1.0, the server implementation does insufficient checks of the certificate provided by the client when doing client authentication, which allows impersonation with certificates that are not meant for client authentication because of KeyUsage and ExtendedKeyUsage...

CVE-2026-45389: Undefined Security Weakness

In OCaml-TLS before 2.1.0, the server implementation does insufficient checks of the certificate provided by the client when doing client authentication, which allows impersonation with certificates that are not meant for client authentication because of KeyUsage and ExtendedKeyUsage...

OSEC-2026-06 TLS-client (with TLS 1.3) does insufficient certificate checks (missing KeyUsage and ExtendedKeyUsage validation)

The ocaml-TLS 1.3 client does not validate the KeyUsage and ExtendedKeyUsage extensions of the server certificate. This can lead to impersonation with a certificate issued to a client. Scenario Every employee at a major bank carries a smart card. The card holds a clientAuth certificate issued by...

PT-2026-42202

Name of the Vulnerable Software and Affected Versions OCaml-TLS versions prior to 2.1.0 Description The client implementation in OCaml-TLS fails to properly validate the KeyUsage and ExtendedKeyUsage EKU extensions of server certificates during TLS 1.3 handshakes. Specifically, the answer...