Vulnerability · Published Oct 13, 2026 · Assigned by libreswan
CVE-2026-77206IKEv2 pre-authentication Null Pointer Dereference in EAP code
High 7.5
In plain English
A high-severity null pointer dereference in libreswan from The Libreswan Project. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 52% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | libreswan | 4.12-2.el8_10.7 | ALSA-2026:90492 |
| AlmaLinux:9 | libreswan | 4.15-11.el9_8 | ALSA-2026:89748 |
| Alpine:v3.23 | libreswan | 5.3.3-r0 | ALPINE-CVE-2026-77206 |
| Alpine:v3.24 | libreswan | 5.3.3-r0 | ALPINE-CVE-2026-77206 |
| Debian:12 | libreswan | no fix listed | DEBIAN-CVE-2026-77206 |
| Debian:13 | libreswan | no fix listed | DEBIAN-CVE-2026-77206 |
| Rocky Linux:8 | libreswan | 0:4.12-2.el8_10.7 | RLSA-2026:90492 |
| Rocky Linux:9 | libreswan | 0:4.15-11.el9_8 | RLSA-2026:89748 |
| Ubuntu:22.04:LTS | libreswan | no fix listed | UBUNTU-CVE-2026-77206 |
| Ubuntu:24.04:LTS | libreswan | no fix listed | UBUNTU-CVE-2026-77206 |
| Ubuntu:26.04:LTS | libreswan | no fix listed | UBUNTU-CVE-2026-77206 |
| Ubuntu:26.10 | libreswan | no fix listed | UBUNTU-CVE-2026-77206 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| The Libreswan Project | libreswan | 4.7 – through 5.3.25.4 – through 5.4 |
Weakness: CWE-476 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- Libreswan Security Advisory CVE-2026-77206 vendor-advisory
- Libreswan CVE-2026-77206 Patches patch