CVE-2026-50721 : faille moyenne libreswan libreswan (CVSS 5.9)

Libreswan, via the function RSA_authenticate_hash_signature_raw_rsa(), did not correctly verify the length of the authentication hash when the SIG payload of an IKEv1 packet was encoded using PKCS #1 RSA Encryption as per RFC 2313. A remote attacker can use a variation on the Bleichenbacher attack to forge the SIG payload when small public exponents are being used (e.g., e=3), which could lead to impersonation. Additionally, a remote attacker, by encoding a shorter than expected hash in the SIG payload, could trigger an assertion leading to denial-of-service. The daemon aborts and restarts; continued exploitation causes sustained denial of service. Remote code execution is not possible. X.509 certificate verifications of remote IKE peers are not affected.

Sévérité

Moyenne (CVSS 5.9)

Vecteur CVSS

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation active

Non signalée par la CISA

Publication

2 juil. 2026

Dernière mise à jour

9 juil. 2026

• libreswan libreswan

• Fiche CVE-2026-50721 sur le NVD (NIST)
• libreswan.org/security/CVE-2026-50721/
• libreswan.org/security/CVE-2026-50721/CVE-2026-50721.txt
• libreswan.org/security/CVE-2026-50722/CVE-2026-50722.txt
• rfc-editor.org/rfc/rfc2313