CVE-2026-12413: Libreswan

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

An invalidly formatted IKEv2 fragment causes the Libreswan pluto daemon to crash and restart. Continued exploitation would cause a denial of service. The function reassemble_v2_incoming_fragments() would ignore unknown outer payloads but still store these in a fixed size array msg_digest.digest[PAYLIMIT]. An off-by-one error in the assertion PASSERT(logger, md->digest_roof < elemsof(md->digest)) causes the daemon to abort. No remote code execution is possible. Any configuration that allows IKEv2 connections that do not set fragmentation=no are vulnerable. IKEv1 is not affected.

Affected products

• Libreswan Libreswan: from 4.6, before 5.3.1 (fixed in 5.3.1)

Published 2026-07-02. Last modified 2026-07-08.