CVE-2026-73569: fast-xml-parser: Repeated DOCTYPE declarations reset entity expansion limits
fast-xml-parser allows users to process XML from JS object without C/C++ based libraries or callbacks. From 5.9.3 until 5.10.1, src/xmlparser/OrderedObjParser.js processes multiple DOCTYPE declarations within a single XML document and passes each declaration's entities through addInputEntities(). addInputEntities() resets maxTotalExpansions and maxExpandedLength every time it is called, allowing additional DOCTYPE declarations to repeatedly reset the configured entity-expansion limits during one parse operation. A crafted XML document can then cause excessive CPU use, event-loop blocking, memory exhaustion, and process termination. This issue is fixed in version 5.10.1.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
fast-xml-parserto a version that resolves this vulnerability.Fixed in 5.10.1
Event History
Frequently Asked Questions
What is the severity of CVE-2026-73569?
The severity of CVE-2026-73569 is rated at risk level 62.
How do I fix CVE-2026-73569?
To fix CVE-2026-73569, upgrade fast-xml-parser to version 5.10.1 or later.
What is affected by CVE-2026-73569?
CVE-2026-73569 affects the fast-xml-parser versions from 5.9.3 to 5.10.1.
What limitation is introduced by CVE-2026-73569 in the fast-xml-parser?
CVE-2026-73569 allows repeated DOCTYPE declarations to reset entity expansion limits, leading to potential security risks.
Who should be concerned about CVE-2026-73569?
Developers and users of fast-xml-parser versions between 5.9.3 and 5.10.1 should be concerned about CVE-2026-73569.