CVE-2026-83606

High

Description

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. From 0.9.0-beta.9 until 0.9.11, the processing-instruction production in lib/grammar.js lets the greedy S+ separator and lazy Char*? data group repeatedly repartition a long whitespace tail when the required closing ?> is absent. Both parsePI and parseProcessingInstruction apply the expression to the entire remaining source, causing quadratic backtracking during DOMParser.parseFromString() under default options and allowing a small unauthenticated XML input to stall the Node.js event loop. This issue is fixed in @xmldom/xmldom version 0.9.11.

SeverityHigh

CVSS8.7

Exploit probability—

Product@xmldom/xmldom

PublishedSep 1, 2026

First seenSep 1, 2026

Weakness typeCWE-400Uncontrolled resource consumption CWE-1333CWE-1333

How to fix

Update

@xmldom/xmldom0.9.11 or later

Affected products

Product	Affected versions	Fixed in
@xmldom/xmldomnpm	0.9.0-beta.9 ≤ v < 0.9.11	0.9.11

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