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 &#65; 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.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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 &#65; 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. (CVE-2026-33036)

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch 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 processeven when developers     have configured strict limits. This issue has been fixed in version 5.5.6. (CVE-2026-33036)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
463322	Echo: fast-xml-parser: security update to 4.5.5	Tenable Cloud Security	Echo Local Security Checks	Local	high
463322	Echo: fast-xml-parser: security update to 4.5.5	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	high
303270	Linux Distros Unpatched Vulnerability : CVE-2026-33036	Nessus	Misc.	Local	high
438905	SCA: security update for fast-xml-parser (GHSA-8gc5-j5rx-235r)	Tenable Cloud Security	SCA Checks	Local	high
438905	SCA: security update for fast-xml-parser (GHSA-8gc5-j5rx-235r)	Tenable Self-Hosted Container Security	SCA Checks	Local	high

Detections

Analytics

CVE-2026-33036

high

Tenable Plugins

high

high

high

high

high