CVE-2026-77205
LOWDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Exploit Intelligence
Low risk: more likely to be exploited than 8% of all known CVEs.
References
Related Vulnerabilities
Other CWE-772 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2003-0132 | Medium | 5.0 | 87% | - | Fix |
| CVE-2017-14495 | High | 7.5 | 85% | - | Fix |
| CVE-2021-22883 | High | 7.5 | 77% | - | Fix |
| CVE-2024-2398 | High | 8.6 | 36% | - | Fix |
| CVE-2020-9375 | High | 7.5 | 27% | - | - |
| CVE-1999-1127 | High | 7.5 | 18% | - | - |
Common questions
How do I fix CVE-2026-77205?
Published advisories record a fix for 8 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-77205 being actively exploited?
Not that we know of. CVE-2026-77205 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.18% is the estimated probability that it will be exploited in the next 30 days. That is higher than 8% of all scored CVEs.
How severe is CVE-2026-77205?
CVE-2026-77205 has a CVSS v3 base score of 3.7, rated low. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-77205 affect?
Published advisories record a fix for libreswan (Red Hat / RHEL), libreswan (Rocky), libreswan-debugsource (Red Hat / RHEL), libreswan-debugsource (Rocky), and 4 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-16.