Vulnerability · Published Sep 1, 2026 · Assigned by GitHub_M

CVE-2026-83612xmldom: HTML raw-text closing-tag case mismatch causes output amplification

High 8.7

In plain English

A high-severity uncontrolled resource consumption in xmldom from xmldom. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)8.7High

Exploit odds (30 days)0.5%top 55.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. From 0.9.0-beta.1 until 0.9.12, HTML-mode parsing through DOMParser.parseFromString() mishandles a mixed-case closing tag for the script, style, textarea, or title raw-text elements. parseHtmlSpecialContent, selected by isHTMLRawTextElement or isHTMLEscapableRawTextElement, uses a case-sensitive indexOf() and then calls substring() with a missing-close result of negative one, causing unstable parser progression and quadratic output amplification. A small untrusted text/html document can consequently consume disproportionate CPU and memory when parsed and serialized. This issue is fixed in @xmldom/xmldom version 0.9.12.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	node-xmldom	no fix listed	DEBIAN-CVE-2026-83612
Debian:13	node-xmldom	no fix listed	DEBIAN-CVE-2026-83612
Debian:14	node-xmldom	0.9.12-1	DEBIAN-CVE-2026-83612
Ubuntu:22.04:LTS	node-xmldom	no fix listed	UBUNTU-CVE-2026-83612
Ubuntu:24.04:LTS	node-xmldom	no fix listed	UBUNTU-CVE-2026-83612
Ubuntu:26.04:LTS	node-xmldom	no fix listed	UBUNTU-CVE-2026-83612
Ubuntu:26.10	node-xmldom	no fix listed	UBUNTU-CVE-2026-83612
npm	@xmldom/xmldom	0.9.12	GHSA-6mj3-qw4j-hgrw

Affected products (as reported)

Vendor	Product	Versions
xmldom	xmldom	>= 0.9.0-beta.1, < 0.9.12
@xmldom	xmldom	>= 0.9.0-beta.1, < 0.9.12

Weakness: CWE-178, CWE-400 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References

https://github.com/xmldom/xmldom/security/advisories/GHSA-6mj3-qw4j-hgrw x_refsource_CONFIRM
https://github.com/xmldom/xmldom/pull/1071 x_refsource_MISC
https://github.com/xmldom/xmldom/commit/7ced40c06c28d151e996a97045018c3559ae4707 x_refsource_MISC
https://github.com/xmldom/xmldom/releases/tag/0.9.12 x_refsource_MISC