CVE-2026-83611

xmldom: Parser silently accepts a not-well-formed end tag whose name is followed by a line break and trailing content

MEDIUM
6.9
CVSS Score
Published: September 1, 2026 at 02:34 PM UTC
Updated: September 8, 2026 at 09:29 PM UTC
1 product affected across 1 vendor@xmldom

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Severity
MEDIUM6.9
Exploit prediction
EPSS 0.6%
SSVC
PoC

Description

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, DOMParser.parseFromString() can silently accept an end tag such as </a\njunk>, close the element, and discard the trailing content. On 0.9.x, the lib/sax.js end-tag validator inherits the multiline flag from reg(), allowing the first line to satisfy the anchored XML ETag production; older lines have no equivalent residue validation. This parser differential can bypass a parse-before-trust well-formedness gate, although it does not inject the discarded content; onError on 0.9.x and errorHandler on 0.8.x are the relevant reporting interfaces. This issue is fixed in @xmldom/xmldom versions 0.8.15 and 0.9.12; no fixed version is available for xmldom.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.8.15v < 0.9.12<= 0.6.0
Affected range stops below 0.8.15, so it looks safe — our inference, not a vendor statement
Affected range stops below 0.9.12, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.9MEDIUMGitHub_M
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-1286

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