Denial of Service Vulnerability in Libreswan FIPS Mode

CVE-2026-14957

What is CVE-2026-14957?

In FIPS mode, the add_decoded_cert() function in Libreswan can be exploited via a malformed X.509 certificate sent by a remote attacker. The function calls CERT_ExtractPublicKey(), which may return NULL if public key extraction fails, such as when the RSA exponent is set to 0. This can cause an assertion failure that leads the pluto daemon to abort and restart, leading to a denial of service. The vulnerability impacts both IKEv1 and IKEv2, and is only exploitable when the OS and Libreswan are configured in FIPS mode with at least one CA certificate loaded, allowing for exploitation without peer authentication credentials. Configurations relying solely on PreSharedKey (PSK) authentication without CA certificates in the NSS database remain unaffected.

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