CVE-2026-77205: low-severity vulnerability in The Libreswan Project libreswan
Denial of Service via sending bogus X.509 certificates
Published · Updated
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8Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 3.7epss 0.2%
Libreswan in FIPS mode has a vulnerability where badly formed received certificates are rejected, but not deleted from the NSS cache. As a result, any real certificates with the same serial number are rejected as well. This can be abused to lock out legitimate peers from connecting. The add_decoded_cert() function missed a call to CERT_DestroyCertificate() due to an incorrect fix for CVE-2026-14957. Sending bogus certificates with new serial numbers could prevent the real certificates with those serial numbers from connecting until the service has restarted.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Affected products
The Libreswan Project · libreswanRelated CVEs — The Libreswan Project libreswan
In the same product, most dangerous first.
CVE-2026-77206HIGHIKEv2 pre-authentication Null Pointer Dereference in EAP codeEPSS 0.7%CVE-2026-12413HIGHIKEv2 Denial of Service via malformed fragmentationEPSS 0.6%CVE-2026-14957HIGHFIPS mode assertion failure via malicious CERT payloadEPSS 0.5%CVE-2026-77207HIGHNull Pointer Dereference in PKCS#7 bundle with no certificatesEPSS 0.5%CVE-2026-94453HIGHIKEv2 Use-After-Free bug when using IKE-over-TCPEPSS 0.5%CVE-2026-50721HIGHIKEv1 Denial of Service via RSA-SHA1 (PKCS#1 Version 1.5 Encrypted) authentication payloadEPSS 0.4%