---
id: CVE-2026-77205
title: >-
  Libreswan in FIPS mode has a vulnerability where badly formed received
  certificates are rejected, but not deleted from the NSS cache
summary: >-
  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…
severity: low
cvss: 3.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-772
published: '2026-10-13'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T22:18:24.577'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77205'
references:
  - url: 'https://libreswan.org/security/CVE-2026-14957/CVE-2026-14957.txt'
    label: d42dc95b-23f1-4e06-9076-20753a0fb0df
  - url: 'https://libreswan.org/security/CVE-2026-77205/'
    label: d42dc95b-23f1-4e06-9076-20753a0fb0df
  - url: 'https://libreswan.org/security/CVE-2026-77205/CVE-2026-77205.txt'
    label: d42dc95b-23f1-4e06-9076-20753a0fb0df
tags:
  - nvd
ingestedAt: '2026-10-13T23:03:54.749Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.