Event-loop stall via quadratic end-tag backtracking
Published Sep 1, 2026 · Updated Sep 1, 2026
Regular-expression denial of service in xmldom 0.7.0 through 0.8.14 allows remote attackers to stall the Node.js event loop. The release-0.8.x lib/sax.js end-tag path applies an unanchored global trailing-whitespace regex to attacker-controlled tag text, retrying and backtracking quadratically when whitespace precedes a non-whitespace character. DOMParser.parseFromString reaches the path under default options without authentication, blocking the host process while the scan runs.
Summary
What happened
Regular-expression denial of service in xmldom 0.7.0 through 0.8.14 allows remote attackers to stall the Node.js event loop. The release-0.8.x lib/sax.js end-tag path applies an unanchored global trailing-whitespace regex to attacker-controlled tag text, retrying and backtracking quadratically when whitespace precedes a non-whitespace character. DOMParser.parseFromString reaches the path under default options without authentication, blocking the host process while the scan runs.
The record
- CVE
- CVE-2026-83619
- Published
- Sep 1, 2026
- Updated
- Sep 1, 2026
- Vendor
- xmldom
- Product
- xmldom
- Classifications
- CWE-1333, CWE-400, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 1, 2026CVE publishedPublication date reported by the CVE source.
- Sep 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 0.7.0, < 0.8.15
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GHSA-x4fp-j954-r2f4 proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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