# CVE-2026-83618

## Summary

- **CVE ID:** CVE-2026-83618
- **Severity:** HIGH
- **CVSS Score:** 8.7 (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)
- **CWE:** CWE-91, CWE-625
- **Published:** Sep 1, 2026
- **Last Modified:** Sep 4, 2026

## 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.

## Affected Products

- xmldom — xmldom (>= 0.9.10, < 0.9.12)
- @xmldom — xmldom (>= 0.9.10, < 0.9.12)

## References

- [CNA](https://github.com/xmldom/xmldom/security/advisories/GHSA-vr34-hp96-76pp)
- [CNA](https://github.com/xmldom/xmldom/pull/1071)
- [CNA](https://github.com/xmldom/xmldom/commit/7b2ec67e1750daadd0bb06c92e875e726544a362)
- [CNA](https://github.com/xmldom/xmldom/releases/tag/0.9.12)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.33%
- **EPSS Percentile:** 25.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._