CVE-2026-77205
Description
A flaw was found in Libreswan's handling of malformed X.509 certificates when running in FIPS mode. A remote attacker may cause a rejected certificate to remain in the NSS certificate cache, resulting in legitimate certificates with the same serial number being rejected. This can prevent affected peers from establishing connections until the Libreswan service is restarted.
Statement
This vulnerability is rated as having a Low impact because exploitation requires the system to operate in FIPS mode and depends on an adversary correctly guessing or intercepting certificate serial numbers, making attack complexity as high. Furthermore, the issue only produces a targeted denial of service by temporarily preventing legitimate peers with matching serial numbers from connecting, without causing daemon crashes or compromising system data, indicating low impact to Availability.
Mitigation
Disabling FIPS mode will prevent this attack vector. However, disabling FIPS mode may violate security or compliance requirements and should not be used as a workaround without authorization.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 3.7 | N/A | 3.7 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
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