NGINX ngx_http_js_module vulnerability

Summary

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.

Timeline

1. Oct 14, 2026, 2:40 PM UTCCVE published
2. Oct 15, 2026, 3:54 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 15, 2026, 4:43 PM UTCRecord last updated

Affected versions

• F5 NGINX JavaScript

  From 0.7.10 · fixed in 1.0.2

References 1