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.
History

Wed, 02 Sep 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important


Tue, 01 Sep 2026 22:00:00 +0000

Type Values Removed Values Added
First Time appeared Xmldom
Xmldom xmldom
Vendors & Products Xmldom
Xmldom xmldom
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 01 Sep 2026 14:30:00 +0000

Type Values Removed Values Added
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.
Title xmldom PI grammar regex ReDoS: quadratic backtracking on unterminated processing instructions
Weaknesses CWE-1333
CWE-400
References
Metrics cvssV4_0

{'score': 8.7, '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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-09-01T14:21:27.215Z

Updated: 2026-09-01T14:57:43.875Z

Reserved: 2026-08-31T20:36:25.743Z

Link: CVE-2026-83606

cve-icon Vulnrichment

Updated: 2026-09-01T14:57:33.295Z

cve-icon NVD

Status : Received

Published: 2026-09-01T15:17:38.490

Modified: 2026-09-01T15:17:38.490

Link: CVE-2026-83606

cve-icon Redhat

Severity : Important

Publid Date: 2026-09-01T14:21:27Z

Links: CVE-2026-83606 - Bugzilla