Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion') Affecting fast-xml-parser package, versions >=5.9.3 <5.10.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-FASTXMLPARSER-18170229
- published22 Jul 2026
- disclosed21 Jul 2026
- creditCharles Vosburgh
Introduced: 21 Jul 2026
CVE-2026-73569 (opens in a new tab)How to fix?
Upgrade fast-xml-parser to version 5.10.1 or higher.
Overview
fast-xml-parser is a Validate XML, Parse XML, Build XML without C/C++ based libraries
Affected versions of this package are vulnerable to Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion') via the addInputEntities function. An attacker can cause excessive CPU usage, event-loop blocking, memory exhaustion, and process termination by crafting an XML document with repeated DOCTYPE declarations that reset entity expansion limits.
Workaround
This vulnerability can be mitigated by manually checking that multiple DOCTYPE declarations are not present in input contents or by keeping the processEntity flag off.