CVE-2026-77206
IKEv2 pre-authentication Null Pointer Dereference in EAP code
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.
INFO
Published Date :
Oct. 13, 2026, 10:18 p.m.
Last Modified :
Oct. 13, 2026, 10:18 p.m.
Remotely Exploit :
Yes !
Source :
d42dc95b-23f1-4e06-9076-20753a0fb0df
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | d42dc95b-23f1-4e06-9076-20753a0fb0df | ||||
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Update Libreswan to the latest version.
- Ensure IKEv2 EAP handling is correctly configured.
- Monitor pluto daemon stability.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-77206.
| URL | Resource |
|---|---|
| https://libreswan.org/security/CVE-2026-77206/ | |
| https://libreswan.org/security/CVE-2026-77206/CVE-2026-77206.txt |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-77206 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-77206
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-77206 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-77206 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by d42dc95b-23f1-4e06-9076-20753a0fb0df
Oct. 13, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-476 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/77xxx/CVE-2026-77206.json">CVE-2026-77206</a> Added Reference https://libreswan.org/security/CVE-2026-77206/ Added Reference https://libreswan.org/security/CVE-2026-77206/CVE-2026-77206.txt