Heap-based buffer overflow in NGINX JavaScript - CVE-2026-78689
Published: September 7, 2026
Vulnerability identifier: #VU147230
CSH Severity: High
CVSS v4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-78689
CWE-ID: CWE-122
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to potentially execute arbitrary code or cause a denial of service.
The vulnerability exists due to a heap-based buffer overflow in the XML module\'s namespace prefix list parser in ngx_http_js_module when an affected NGINX configuration passes an externally controlled XML namespace prefix list to xml.exclusiveC14n(). A remote attacker can submit a crafted XML namespace prefix list to potentially execute arbitrary code or cause a denial of service.
The official nginxinc/nginx-saml reference implementation processes untrusted SAML namespace prefix lists during signature verification before the signature is verified.
Affected software
NGINX JavaScript
How to mitigate CVE-2026-78689
Install security update from vendor's website.
NGINX JavaScript - update to 1.0.1