TI-2026-73732 Aliases CVE-2026-77205 GHSA-7m29-c28j-rg7h

Denial of service via bogus X.509 certificates in Libreswan

LOW 17CWE-772Published 2026-10-13 · Updated 2026-10-16

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: High
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · Low
Fix status: Partial Red Hat: 1 fixed, 3 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-772.

Summary

The Libreswan Project's libreswan versions from 5.3 through 5.3.2 are affected when running in FIPS mode. Malformed received certificates are rejected but stay in the NSS cache because a required release call is missing in add_decoded_cert() (CWE-772), so real certificates with the same serial number are rejected too. A remote attacker who needs no privileges can send bogus certificates to lock out legitimate peers until the service restarts.

Written with Claude Haiku 5.5 from the sources below · 2026-11-01

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00183 7th percentileScored 2026-11-07

Fix Partial libreswan (The Libreswan Project): 5.3.3Red Hat: 1 advisoryRed Hat: 1 fixed, 3 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
The Libreswan Project	libreswan	5.3 – 5.3.2	5.3.3	Patch available	CNA

libreswan VendorThe Libreswan Project Affected 5.3 – 5.3.2 Fixed in 5.3.3 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:libreswan:libreswan::::::::	—	—	The Libreswan Project

cpe:2.3:a:libreswan:libreswan:*:*:*:*:*:*:*:* Versions — — ·The Libreswan Project

Remediation

Update libreswan to version 5.3.3. Red Hat Enterprise Linux AppStream (v. 10) is fixed by RHSA-2026:89923. The sources list no fixed version for Fast Datapath for RHEL 9, Red Hat OpenShift Container Platform 4 and Red Hat OpenShift Container Platform 5.

Written with Claude Haiku 5.5 from the sources below · 2026-11-01

Fix · CNA libreswan (The Libreswan Project) Fixed in 5.3.3

Red Hat 1 advisory

RHSA-2026:89923 Released 2026-10-26 · Red Hat rating Important
libreswan security update
- Red Hat Enterprise Linux AppStream (v. 10) libreswan-5.3.3-1.el10_2, libreswan-minimal-5.3.3-1.el10_2

Vendor assessments

Red Hat

Red Hat rating: Low. Red Hat's page for this CVE →

Product	Status	Plan or fix
Fast Datapath for RHEL 9	Affected	No fix yet
Red Hat OpenShift Container Platform 4	Affected	No fix yet
Red Hat OpenShift Container Platform 5	Affected	No fix yet
Red Hat Enterprise Linux AppStream (v. 10)	Fixed	RHSA-2026:89923

Not affected: 5 products

Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 8
Red Hat Enterprise Linux 9
Red Hat OpenShift Container Platform 4

Timeline

2026-10-13 Threatist record created from CVE-2026-77205
2026-10-14 Alias added: GHSA-7m29-c28j-rg7h
2026-10-15 Affected versions changed · Red Hat
2026-10-15 CVSS score added · Red Hat
2026-10-16 CISA SSVC decision points changed
2026-10-26 Fix available: RHSA-2026:89923 · Red Hat
2026-10-26 Fix available: Red Hat Enterprise Linux AppStream (v. 10) · Red Hat
2026-11-01 Affected versions changed · Red Hat

References

TI-2023-09114 Libreswan 4.9 allows remote attackers to cause a denial of service (assert failure and… CVSS 3.1MEDIUM 6.5
TI-2013-05949 Race condition in the libreswan.spec files for Red Hat Enterprise Linux (RHEL) and Fedora… CVSS 2.0HIGH 9.3
TI-2023-02152 Uncontrolled resource consumption in libreswan CVSS 3.1HIGH 7.5
TI-2026-37395 IKEv2 Denial of Service via RSA-SHA1 (PKCS#1 RSASSA-PKCS1-v1_5) authentication payload CVSS 3.1HIGH 8.1
TI-2026-37394 IKEv1 Denial of Service via RSA-SHA1 (PKCS#1 Version 1.5 Encrypted) authentication payload CVSS 3.1HIGH 8.1
TI-2023-14401 pluto in Libreswan before 4.11 allows a denial of service (responder SPI mishandling and… CVSS 3.1HIGH 7.5

See all 28 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences