CVE-2026-77206 IKEv2 pre-authentication Null Pointer Dereference in EAP code
A malicious IKE_AUTH packet can trigger a null pointer dereference in Libreswan, causing a daemon crash and denial of service without authentication.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-77206?
CVE-2026-77206 is a high-severity vulnerability in The Libreswan Project libreswan, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Libreswan's IKEv2 state machine has a null pointer dereference bug in the EAP handling code for authentication. As a result of inconsistency within the IKEv2 state machine code, this bug can be triggered by any IKEv2 connection, even if EAP is not configured at all. The error is caused by a fall-through where it incorrectly dereferences ike->sa.st_eap which is NULL. A malicious IKE_AUTH packet can trigger this bug, meaning the peer does not need to be authenticated. The bug results in a crash and restart of the pluto daemon. No remote code execution is possible. Continued exploitation can cause a denial of service.
Weakness: CWE-476
Which versions are affected by CVE-2026-77206?
How do I fix CVE-2026-77206?
Apply the vendor's patch.
Is CVE-2026-77206 being exploited?
There is no known exploitation of CVE-2026-77206 in the wild and no public exploit code.
Sources
Also known as AZL-108030, DEBIAN-CVE-2026-77206, GHSA-37xg-hvw9-pr82, UBUNTU-CVE-2026-77206.