XML Entity Expansion in fast-xml-parser - CVE-2026-33036

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Main Vulnerability Database Vulnerabilities #VU126615

XML Entity Expansion in fast-xml-parser - CVE-2026-33036

Published: April 20, 2026


Vulnerability identifier: #VU126615
CSH Severity: Medium
CVSS v4: 8.7 [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]
CVE-ID: CVE-2026-33036
CWE-ID: CWE-776
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to improper restriction of entity expansion in replaceEntitiesValue() in src/xmlparser/OrderedObjParser.js when parsing XML input containing numeric character references or standard XML entities. A remote attacker can send specially crafted XML input with massive numbers of numeric entity references to cause a denial of service.

The configured entity expansion limits are enforced only for DOCTYPE-defined entities, while numeric character references and standard XML entities are processed through a separate code path without expansion counting.


Affected software

fast-xml-parser
Cognos Analytics Mobile (iOS)
Cognos Analytics Mobile (Android)
IBM App Connect Enterprise
OpenShift Data Foundation (formerly OpenShift Container Storage)

How to mitigate CVE-2026-33036

Install security update from vendor's website.

fast-xml-parser - addressed in versions 4.5.5, 5.5.6
Cognos Analytics Mobile (iOS) - update to 1.1.26
Cognos Analytics Mobile (Android) - update to 1.1.26
IBM App Connect Enterprise - addressed in versions 12.0.12.26, 13.0.7.2
OpenShift Data Foundation (formerly OpenShift Container Storage) - addressed in versions 4.18.25, 4.19.20

External References

Related Security Bulletins