Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| The Libreswan Project | libreswan | 5.3 – ≤ 5.3.2 | 5.3.3 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | libreswan | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | libreswan | No fix yet | — |
| Ubuntu 26.04 LTS | libreswan | No fix yet | — |
| Ubuntu 24.04 LTS | libreswan | No fix yet | — |
| Ubuntu 22.04 LTS | libreswan | No fix yet | — |
| Ubuntu 20.04 LTS | libreswan | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | libreswan | No fix yet | — |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | libreswan +1 | 5.3.3-1.el10_2 | ALSA-2026:89923 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | libreswan | 5.3.3-1.el10_2 | RLSA-2026:89923 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | libreswan | 5.3.3-r0 | — |
| Alpine v3.23 | libreswan | 5.3.3-r0 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | libreswan +1 | 5.3.3-1.0.1.el10_2 | ELSA-2026-89923 |
Advisories 4
- WID-SEC-2026-4183 Red Hat Enterprise Linux Libreswan: Mehrere Schwachstellen ermöglichen Denial of Service BSI CERT-Bund (WID) · Nov 10, 2026
- ALSA-2026:89923 Important: libreswan security update AlmaLinux Security Advisories · Oct 29, 2026
- RLSA-2026:89923 Important: libreswan security update Rocky Linux Security Advisories · Oct 27, 2026
- ELSA-2026-89923 Important: libreswan security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Oct 26, 2026