Amazon Linux 2023 Security Advisory: ALAS2023-2026-3300
Advisory Released Date: 2026-10-24
Advisory Updated Date: 2026-10-26
Description
NGINX JavaScript (njs) has a vulnerability where the njs XML module exposes entity-backed XML attributes inconsistently with libxml2 canonicalization. In both the built-in njs and QuickJS backends during the canonicalization process, the $attr$Name getter may return undefined for an explicitly present attribute containing an internal entity reference. The $attrs getter may return a value derived only from the first attribute child. This may allow an unauthenticated attacker that invests significant effort in obtaining a genuinely signed document to skip validation while signature verification succeeds. An nginx-saml deployment is a confirmed affected consumer when run with the built-in njs backend.
Impact
In affected signed-XML consumers, an unauthenticated attacker can cause security-relevant attributes to appear absent or truncated while signature verification succeeds. In nginx-saml, this can bypass expiry, Destination, and request-correlation checks, enabling replay or acceptance of a response outside its intended context. It does not permit signature or identity forgery, or a direct availability impact. There is no control plane exposure; this is a data plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. (CVE-2026-101019)
Description
NGINX JavaScript (njs) has a vulnerability where the built-in njs engine leaks a libxml2 parser context when xml.parse() fails. The failure path did not register cleanup and the context was not released for the lifetime of the process. An unauthenticated attacker may send requests with malformed XML and can cause unbounded memory growth in long-lived NGINX worker processes.
Impact
This vulnerability may allow remote attackers to send requests that trigger repeated parsing of malformed XML and may lead to NGINX worker termination or denial of service. There is no control plane exposure; this is a data plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. (CVE-2026-101025)
Affected Packages:
nginx-mod-njs
Issue Correction:
Run dnf update nginx-mod-njs --releasever 2023.12.20261026 or dnf update --advisory ALAS2023-2026-3300 --releasever 2023.12.20261026 to update your system.
More information on how to update your system can be found on this page: Amazon Linux 2023 documentation
aarch64:
nginx-mod-njs-debuginfo-1.0.2-1.amzn2023.0.1.aarch64
nginx-mod-njs-debugsource-1.0.2-1.amzn2023.0.1.aarch64
nginx-mod-njs-1.0.2-1.amzn2023.0.1.aarch64
src:
nginx-mod-njs-1.0.2-1.amzn2023.0.1.src
x86_64:
nginx-mod-njs-debuginfo-1.0.2-1.amzn2023.0.1.x86_64
nginx-mod-njs-debugsource-1.0.2-1.amzn2023.0.1.x86_64
nginx-mod-njs-1.0.2-1.amzn2023.0.1.x86_64