7.5

CVE-2026-33036

Exploit
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.
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Naturalintelligence ≫ Fast-xml-parser Version >= 4.0.1 < 5.5.6
Naturalintelligence ≫ Fast-xml-parser Version4.0.0 Update-
Naturalintelligence ≫ Fast-xml-parser Version4.0.0 Updatebeta3
Naturalintelligence ≫ Fast-xml-parser Version4.0.0 Updatebeta4
Naturalintelligence ≫ Fast-xml-parser Version4.0.0 Updatebeta5
Naturalintelligence ≫ Fast-xml-parser Version4.0.0 Updatebeta6
Naturalintelligence ≫ Fast-xml-parser Version4.0.0 Updatebeta7
Naturalintelligence ≫ Fast-xml-parser Version4.0.0 Updatebeta8
Zu dieser CVE wurde keine CISA KEV oder CERT.AT-Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.05% 0.163
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
security-advisories@github.com 7.5 3.9 3.6
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE-776 Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')

The product uses XML documents and allows their structure to be defined with a Document Type Definition (DTD), but it does not properly control the number of recursive definitions of entities.