---
id: CVE-2026-101019
title: >-
  Description

  NGINX JavaScript (njs) has a vulnerability where the njs XML module exposes
  entity-backed XML attributes inconsistently with libxml2 canonicalization
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 …
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N'
cwe:
  - CWE-436
published: '2026-10-14'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T16:04:11.750'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-101019'
references:
  - url: 'https://my.f5.com/manage/s/article/K000162615'
    label: f5sirt@f5.com
tags:
  - nvd
ingestedAt: '2026-10-14T15:36:13.995Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.