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Vulnerability · Published Sep 2, 2026 · Assigned by libreswan

CVE-2026-14957FIPS mode assertion failure via malicious CERT payload

High 7.5

In plain English

A high-severity security flaw 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 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.5%top 59.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

In FIPS mode, Libreswan's add_decoded_cert() function calls CERT_ExtractPublicKey() and asserts that the result is not NULL. However, CERT_ExtractPublicKey() returns NULL when public key extraction fails, for example if the RSA exponent is set to 0. A remote attacker can send a malformed X.509 certificate in a CERT payload to trigger the assertion, causing the pluto daemon to abort and restart. Continued exploitation causes a denial of service. No remote code execution is possible. Both IKEv1 and IKEv2 are affected. The vulnerability is only exploitable when both the OS and libreswan are running in FIPS mode and at least one CA certificate is loaded. The CERT payload is processed before peer authentication, so no credentials are needed to exploit this. Configurations using only PreSharedKey (PSK) authentication with no CA certificates loaded in the NSS database are not vulnerable.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:10libreswan5.3.2-1.el10_2ALSA-2026:46398
AlmaLinux:8libreswan4.12-2.el8_10.6ALSA-2026:46396
AlmaLinux:9libreswan4.15-10.el9_8ALSA-2026:46397
AlmaLinux:10libreswan-minimal5.3.2-1.el10_2ALSA-2026:46398
Alpine:v3.23libreswan5.3.3-r0ALPINE-CVE-2026-14957
Alpine:v3.24libreswan5.3.2-r0ALPINE-CVE-2026-14957
Debian:12libreswanno fix listedDEBIAN-CVE-2026-14957
Debian:13libreswanno fix listedDEBIAN-CVE-2026-14957
Rocky Linux:10libreswan0:5.3.2-1.el10_2RLSA-2026:46398
Rocky Linux:8libreswan0:4.12-2.el8_10.6RLSA-2026:46396
Rocky Linux:9libreswan0:4.15-10.el9_8RLSA-2026:46397
Ubuntu:22.04:LTSlibreswanno fix listedUBUNTU-CVE-2026-14957
Ubuntu:24.04:LTSlibreswanno fix listedUBUNTU-CVE-2026-14957
Ubuntu:26.04:LTSlibreswanno fix listedUBUNTU-CVE-2026-14957
Ubuntu:26.10libreswanno fix listedUBUNTU-CVE-2026-14957

Affected products (as reported)

VendorProductVersions
The Libreswan Project libreswan 3.0 – through 5.3.1

Weakness: CWE-617, CWE-252 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References