Amazon Linux 2 (EOS) Security Advisory: ALAS2-2026-4021
Advisory Released Date: 2026-10-24
Advisory Updated Date: 2026-10-26
Severity:
Important
Issue Overview:
A null pointer dereference flaw was found in Libreswan's PKCS#7 certificate payload handling. When processing a crafted IKEv2 IKE_AUTH packet containing a PKCS#7 bundle with a certificate revocation list but no certificates, Libreswan may dereference a null pointer, causing the pluto daemon to crash and restart. A remote, unauthenticated attacker could repeatedly trigger this flaw to cause a denial of service. (CVE-2026-77207)
Affected Packages:
libreswan
Note:
This advisory is applicable to Amazon Linux 2 (AL2) Core repository. Visit this FAQ section for the difference between AL2 Core and AL2 Extras advisories.
Issue Correction:
Run yum update libreswan or yum update --advisory ALAS2-2026-4021 to update your system.
New Packages:
aarch64:
libreswan-3.25-4.8.amzn2.0.4.aarch64
libreswan-debuginfo-3.25-4.8.amzn2.0.4.aarch64
i686:
libreswan-3.25-4.8.amzn2.0.4.i686
libreswan-debuginfo-3.25-4.8.amzn2.0.4.i686
src:
libreswan-3.25-4.8.amzn2.0.4.src
x86_64:
libreswan-3.25-4.8.amzn2.0.4.x86_64
libreswan-debuginfo-3.25-4.8.amzn2.0.4.x86_64