F5 NGINX JavaScript up to 1.0.1 XML module $attr$Name/$attrs signature verification

Summaryinfo

A vulnerability identified as critical has been detected in F5 NGINX JavaScript up to 1.0.1. Affected by this vulnerability is the function $attr$Name/$attrs of the component XML module. Performing a manipulation results in signature verification. This vulnerability is known as CVE-2026-101019. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in F5 NGINX JavaScript up to 1.0.1. This affects the function $attr$Name/$attrs of the component XML module. The manipulation with an unknown input leads to a signature verification vulnerability. CWE is classifying the issue as CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at my.f5.com. This vulnerability is uniquely identified as CVE-2026-101019 since 09/30/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available.

Upgrading to version 1.0.2 eliminates this vulnerability.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Web Server

Vendor

• F5

Name

• NGINX JavaScript

Version

• 1.0.0
• 1.0.1

License

• commercial

Website

• Vendor: https://f5.com/

CPE 2.3info

• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Discussion