Heap-based Buffer Overflow Affecting libnginx-mod-js package, versions *


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.76% (54th percentile)

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  • Snyk IDSNYK-ECHOLATEST-LIBNGINXMODJS-19512314
  • published3 Sept 2026
  • disclosed2 Sept 2026

Introduced: 2 Sep 2026

CVE-2026-78689  (opens in a new tab)
CWE-122  (opens in a new tab)

How to fix?

There is no fixed version for Echo:latest libnginx-mod-js.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libnginx-mod-js package and not the libnginx-mod-js package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

Description

NGINX JavaScript (njs) has a vulnerability in the XML module's namespace prefix list parser, reachable through the xml.exclusiveC14n() method. An unauthenticated remote attacker can trigger it when an affected NGINX configuration passes an externally controlled XML namespace prefix list to that method. Both the njs and the QuickJS (qjs) engines are affected. A crafted prefix list causes an out-of-bounds write past the end of a heap allocation. With the njs engine, which is the engine used when the js_engine directive is absent, this corrupts adjacent objects and crashes the NGINX worker. With the QuickJS engine, the same call additionally leaks the prefix list on every invocation, causing worker memory to grow across requests. The official nginxinc/nginx-saml reference implementation is affected during SAML signature verification. It reads InclusiveNamespaces/@PrefixList from an untrusted SAML message and passes it to xml.exclusiveC14n() before the signature has been verified, so a valid SAML signature is not required. A crafted SAML Response, Assertion, LogoutRequest, or LogoutResponse is sufficient. Code execution has not been demonstrated and cannot be ruled out for all platforms, as the effect of the out-of-bounds write depends on conditions beyond the attacker's control.  

Impact

This vulnerability allows remote attackers to cause a denial of service on the NGINX system, either through repeatable worker restarts or through worker memory growth or possibly trigger code execution. 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.

CVSS Base Scores

version 3.1