CVE-2026-33036

Published: Mar 20, 2026 Last Modified: Mar 20, 2026
ExploitDB:
Other exploit source:
Google Dorks:
HIGH 7,5
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: none
User Interaction: none
Scope: unchanged
Confidentiality: none
Integrity: none
Availability: high

Description

AI Translation Available

fast-xml-parser allows users to process XML from JS object without C/C++ based libraries or callbacks. Versions 4.0.0-beta.3 through 5.5.5 contain a bypass vulnerability where numeric character references (&#NNN;, &#xHH;) and standard XML entities completely evade the entity expansion limits (e.g., maxTotalExpansions, maxExpandedLength) added to fix CVE-2026-26278, enabling XML entity expansion Denial of Service. The root cause is that replaceEntitiesValue() in OrderedObjParser.js only enforces expansion counting on DOCTYPE-defined entities while the lastEntities loop handling numeric/standard entities performs no counting at all. An attacker supplying 1M numeric entity references like A can force ~147MB of memory allocation and heavy CPU usage, potentially crashing the process—even when developers have configured strict limits. This issue has been fixed in version 5.5.6.

776

Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')

Draft
Abstraction: Base Structure: Simple
Common Consequences
Security Scopes Affected:
Availability
Potential Impacts:
Dos: Resource Consumption (Other)
Applicable Platforms
Languages: Not Language-Specific, XML
Likelihood of Exploit: Medium
View CWE Details
https://github.com/NaturalIntelligence/fast-xml-parser/comm…
https://github.com/NaturalIntelligence/fast-xml-parser/commit/bd26122c838e6a55e…
https://github.com/NaturalIntelligence/fast-xml-parser/rele…
https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.5.6
https://github.com/NaturalIntelligence/fast-xml-parser/secu…
https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA…