Application freeze via unbounded DOCTYPE entity replacement
Published Feb 19, 2026 · Updated Aug 26, 2026
Denial of service in fast-xml-parser 4.1.3 through 4.5.3 and 5.0.0 through 5.3.5 allows remote attackers to freeze applications. replaceEntitiesValue() in OrderedObjParser.js repeatedly applies val.replace() to raw-text DOCTYPE entity references without limiting output size, replacement count, or execution cost. Exposure requires a service to parse attacker-supplied XML with entity processing enabled; the resulting work blocks the Node.js event loop and interrupts every request handled by the process.
Summary
What happened
Denial of service in fast-xml-parser 4.1.3 through 4.5.3 and 5.0.0 through 5.3.5 allows remote attackers to freeze applications. replaceEntitiesValue() in OrderedObjParser.js repeatedly applies val.replace() to raw-text DOCTYPE entity references without limiting output size, replacement count, or execution cost. Exposure requires a service to parse attacker-supplied XML with entity processing enabled; the resulting work blocks the Node.js event loop and interrupts every request handled by the process.
The record
- CVE
- CVE-2026-26278
- Published
- Feb 19, 2026
- Updated
- Aug 26, 2026
- Vendor
- 389 Directory Server
- Product
- Red Hat Developer Hub
- Classifications
- CWE-776, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 19, 2026CVE publishedPublication date reported by the CVE source.
- Aug 26, 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?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
What conditions does exploitation require?
What is affected?
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-jmr7-xgp7-cmfj entity-expansion proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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