Libreswan Project up to 5.3.2 add_decoded_cert denial of service

CVSS Meta Temp Score
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CTI Interest Score
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5.5$0-$5k0.00

Summaryinfo

A vulnerability categorized as critical has been discovered in Libreswan Project Libreswan up to 5.3.2. This vulnerability affects the function add_decoded_cert. Such manipulation leads to denial of service. This vulnerability is traded as CVE-2026-77205. The attack may be launched remotely. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Libreswan Project Libreswan up to 5.3.2. It has been rated as critical. Affected by this issue is the function add_decoded_cert. The manipulation with an unknown input leads to a denial of service vulnerability. Using CWE to declare the problem leads to CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. Impacted is availability. CVE summarizes:

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.

The advisory is available at libreswan.org. This vulnerability is handled as CVE-2026-77205 since 08/20/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 5.3.3 eliminates this vulnerability.

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Productinfo

Type

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.6
VulDB Meta Temp Score: 5.5

VulDB Base Score: 7.5
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 3.7
CNA Vector (libreswan): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Denial of service
CWE: CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Libreswan 5.3.3

Timelineinfo

08/20/2026 CVE reserved
10/13/2026 +54 days VulDB entry created
10/14/2026 +0 days Advisory disclosed
10/14/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: libreswan.org
Status: Confirmed

CVE: CVE-2026-77205 (🔒)
GCVE (CVE): GCVE-0-2026-77205
GCVE (VulDB): GCVE-100-418454

Entryinfo

Created: 10/14/2026 00:14
Changes: 10/14/2026 00:14 (64)
Complete: 🔍
Cache ID: 216::103

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