# 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.

- **Severity:** High 8.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-108452, BELL-CVE-2026-101019, DEBIAN-CVE-2026-101019, GHSA-fvf3-54p5-jg2m, UBUNTU-CVE-2026-101019

## 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 (Interpretation Conflict)

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-101019 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-101019 in the wild and no public exploit code.

Affected product: F5 NGINX JavaScript. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-101019/ (Markdown: https://insights.sbomify.com/CVE-2026-101019/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-101019
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-101019
- OSV: https://osv.dev/vulnerability/CVE-2026-101019

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-101019/
Summaries are generated and may contain mistakes; the official description above is the record.