CVE-2026-77207: CWE-476: Null Pointer Dereference in The Libreswan Project libreswan
Description
CVE-2026-77207 is a high-severity vulnerability in Libreswan affecting versions from 4.7 through 5.3.2 and 5.4 through 5.4. It involves a null pointer dereference in the PKCS#7 handling code used for IKE certificate authentication. This flaw can be triggered by a malicious IKE_AUTH packet, causing the Libreswan process to crash and restart, resulting in a denial of service. No remote code execution or data compromise is possible.
CVSS v3.1
Score 7.5high
Affected software
The Libreswan Project
libreswan
pkg:github/libreswanRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Libreswan contains a null pointer dereference vulnerability in its PKCS#7 handling code for IKE certificate authentication. Specifically, when decoding an IKE CERT payload of type CERT_PKCS7_WRAPPED_X509, Libreswan uses two NSS APIs: SEC_PKCS7ContainsCertsOrCrls() and SEC_PKCS7GetCertificateList(). These APIs disagree when a SignedData structure carries a CRL but no certificates. The first API returns true, allowing processing to continue, but the second returns NULL, leading to a null pointer dereference and crash. An attacker can send a crafted IKE_AUTH packet to trigger this bug without needing to authenticate, causing a denial of service via process crash and restart. No remote code execution is possible.
Potential Impact
Successful exploitation causes a denial of service by crashing the Libreswan process handling IKE certificate authentication. The crash occurs due to a null pointer dereference when processing a specially crafted IKE_AUTH packet. There is no impact on confidentiality or integrity, and no remote code execution is possible.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a patch is available, consider limiting exposure to untrusted IKE peers or implementing network-level protections to block malicious IKE_AUTH packets. Monitor for updates from the Libreswan Project regarding an official fix.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- libreswan
- Date Reserved
- 2026-08-20T18:13:09.377Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6acea4042cdf04f656b3059e
Added to database: 10/13/2026, 21:35:00 UTC
Last enriched: 10/13/2026, 21:48:27 UTC
Last updated: 10/13/2026, 21:50:44 UTC
Views: 5
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