CVE-2026-101019 NGINX ngx_http_js_module vulnerability
An unauthenticated attacker can bypass SAML security checks like expiry and destination validation by exploiting inconsistent XML attribute handling in NGINX JavaScript.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-101019?
CVE-2026-101019 is a high-severity vulnerability in F5 NGINX JavaScript, published on 14 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-436
Which versions are affected by CVE-2026-101019?
How do I fix CVE-2026-101019?
Upgrade to a fixed version.
Is CVE-2026-101019 being exploited?
There is no known exploitation of CVE-2026-101019 in the wild and no public exploit code.
Sources
Also known as AZL-108452, BELL-CVE-2026-101019, DEBIAN-CVE-2026-101019, GHSA-fvf3-54p5-jg2m, UBUNTU-CVE-2026-101019.