What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 8.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-01 · updated 2026-09-08
• Weakness: CWE-178

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 products

• xmldom: from 0.9.0-beta.1, < 0.9.12

References

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

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