What’s Vulnerable › Vulnerabilities

CVE-2026-12413: IKEv2 Denial of Service via malformed fragmentation

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-02 · updated 2026-10-25
• Weakness: CWE-193

Description

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

• The Libreswan Project libreswan: from 4.6 before 5.3.1 — fixed in 5.3.1

How to fix

Upgrade to a fixed version: The Libreswan Project libreswan 5.3.1. Check the vendor advisory for mitigations.

References

• https://libreswan.org/security/CVE-2026-12413/
• https://libreswan.org/security/CVE-2026-12413/CVE-2026-12413.txt

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