CVE-2026-77206: IKEv2 pre-authentication Null Pointer Dereference in EAP code
IKEv2 pre-authentication Null Pointer Dereference in EAP code
Other sources
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.steap which is NULL. A malicious IKEAUTH 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.
— MITRE
The Libreswan Project was informed of a Null Pointer Dereference bug in the EAP handling code for authentication that can result in a denial of service against the libreswan pluto daemon.
As a result of inconsistency within the IKEv2 state machine code, a bug can be triggered by any IKEv2 connection, even if EAP is not configured at all. The bug results in a crash and restart. No remote code execution is possible. The error is caused by a fall-through error where it incorrectly dereferences ike->sa.steap which is NULL.
An malicious IKEAUTH packet can trigger this bug, meaning the peer need not be authenticated. Continued attempts to use IKEv2 with such malicious payloads can cause a denial of service. No remote code execution is possible.
Vulnerable versions : 4.7 - 5.4 Not vulnerable : 5.3.3, 5.4.1
— Red Hat
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
alpine/libreswanto a version that resolves this vulnerability.Fixed in 5.3.3-r0 - Upgrade
Upgrade
libreswanto a version that resolves this vulnerability.Fixed in 5.4.1
Event History
Frequently Asked Questions
Are deployments that do not use EAP still affected?
Yes. The flaw can be triggered by any IKEv2 connection because of an IKEv2 state-machine inconsistency, even when EAP is not configured.
Does an attacker need valid VPN credentials or prior authentication?
No. A malicious IKE_AUTH packet can trigger the issue before the peer is authenticated, so no credentials or prior access are required.
What is the practical impact of successful exploitation?
Successful exploitation crashes and restarts the pluto daemon. Repeated malicious packets can therefore cause a denial of service; remote code execution is not possible.