CVE-2026-83606
xmldom PI grammar regex ReDoS: quadratic backtracking on unterminated processing instructions
- State
- Published
- Severity
- 8.7 High
- Published
- Sep 1, 2026
- Updated
- Sep 1, 2026
- Reserved
- Aug 31, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.7 High | 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 | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
xmldomxmldom |
|
xmldom@xmldom |
|
References
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