CVE-2026-83618 xmldom: requireWellFormed DocType publicId/systemId validation is bypassable via an embedded line terminator
Attackers can bypass XML serialization validation to inject malicious markup, potentially leading to code execution in applications using xmldom.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-83618?
CVE-2026-83618 is a high-severity code injection vulnerability in @xmldom xmldom, published on 1 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. From 0.9.10 until 0.9.12, the requireWellFormed: true serializer validates DocumentType.publicId and DocumentType.systemId with PubidLiteral_match and SystemLiteral_match expressions produced by reg() in lib/grammar.js, which inherit the multiline flag. A complete valid literal on the first line can therefore satisfy the matcher while U+000A, U+000D, U+2028, or U+2029 and breakout markup remain in the emitted <!DOCTYPE ...> declaration. This bypasses the strict-serialization mitigation for the earlier DocumentType injection advisory; creation and direct property assignment remain unvalidated by design. This issue is fixed in @xmldom/xmldom version 0.9.12.
Which versions are affected by CVE-2026-83618?
2 open source packages ship an affected version, including @xmldom/xmldom.
| Package | Affected | Fixed in |
|---|---|---|
@xmldom/xmldom npm | From 0.9.10 | 0.9.12 |
@xmldom/xmldom npm | From 0.9.10 | 0.9.12 |
How do I fix CVE-2026-83618?
Upgrade @xmldom/xmldom to 0.9.12 or later.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-83618 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-83618 exists.
Sources
Also known as DEBIAN-CVE-2026-83618, GHSA-vr34-hp96-76pp, ROOT-APP-NPM-CVE-2026-83618, UBUNTU-CVE-2026-83618.