CVE-2026-83616 HIGH

CVE-2026-83616: xmldom: Processing Instruction Target Injection Bypasses requireWellFormed

Vendor Xmldom
Product xmldom
Weakness CWE-91 · XML injection
Published September 1, 2026
Last update September 1, 2026

CVSS base score

8.7/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

What the vulnerability does

01Description

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. Prior to @xmldom/xmldom versions 0.8.15 and 0.9.12, and in xmldom version 0.6.0 and earlier, Document.createProcessingInstruction(target, data) in lib/dom.js accepts an unvalidated target, while the requireWellFormed: true serializer checks only for a colon and the reserved case-insensitive xml name on 0.9.x and performs no target check on 0.8.x. Because serialization emits <?target data?>, a target containing >, ?, whitespace, or another invalid XML-name character can break the processing-instruction boundary and inject XML structure. This issue is fixed in @xmldom/xmldom versions 0.8.15 and 0.9.12; no fixed version is available for xmldom.

Key dates

02Disclosure timeline

September 1, 2026 CVE published
September 1, 2026 Record updated