fast-xml-parser affected by DoS through entity expansion in DOCTYPE (no expansion limit)

MITRE NVD CVE.ORG JSON API Print: PDF PDF

Summary

CVECVE-2026-26278
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-02-19 20:25:43 UTC
Updated2026-06-30 03:17:49 UTC
Descriptionfast-xml-parser allows users to validate XML, parse XML to JS object, or build XML from JS object without C/C++ based libraries and no callback. In versions 4.1.3 through 5.3.5, the XML parser can be forced to do an unlimited amount of entity expansion. With a very small XML input, it’s possible to make the parser spend seconds or even minutes processing a single request, effectively freezing the application. Version 5.3.6 fixes the issue. As a workaround, avoid using DOCTYPE parsing by `processEntities: false` option.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-776 | CWE-776 CWE-776: Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion') | CWE-776 Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')

VersionSourceTypeScoreSeverityVector
3.1ADPCVSS7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.10b0ca135-0b70-47e7-9f44-1890c2a1c46cSecondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Naturalintelligence Fast-xml-parser All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA NaturalIntelligence Fast-xml-parser affected >= 5.0.0, < 5.3.6 Not specified
CNA NaturalIntelligence Fast-xml-parser affected >= 4.1.3, < 4.5.4 Not specified
ADP Red Hat Red Hat Advanced Cluster Security For Kubernetes 4.8 Not specified Not specified
ADP Red Hat Red Hat Advanced Cluster Security For Kubernetes 4.9 Not specified Not specified
ADP Red Hat Red Hat Developer Hub 1.8 Not specified Not specified
ADP Red Hat Red Hat Developer Hub 1.9 Not specified Not specified
ADP Red Hat Migration Toolkit For Applications 8 Not specified Not specified
ADP Red Hat Red Hat Openshift Data Foundation 4 Not specified Not specified
ADP Red Hat Red Hat OpenShift GitOps Not specified Not specified
ADP Red Hat Red Hat OpenShift Virtualization 4 Not specified Not specified
ADP Red Hat Red Hat Satellite 6 Not specified Not specified
ADP Red Hat Self-service Automation Portal 2 Not specified Not specified

References

ReferenceSourceLinkTags
access.redhat.com/errata/RHSA-2026:6802 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
bugzilla.redhat.com/show_bug.cgi 0b0ca135-0b70-47e7-9f44-1890c2a1c46c bugzilla.redhat.com
access.redhat.com/errata/RHSA-2026:6174 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.3.6 [email protected] github.com Product, Release Notes
access.redhat.com/errata/RHSA-2026:7110 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:7128 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/security/cve/CVE-2026-26278 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-... [email protected] github.com Exploit, Vendor Advisory
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-26278.json 0b0ca135-0b70-47e7-9f44-1890c2a1c46c security.access.redhat.com
github.com/NaturalIntelligence/fast-xml-parser/commit/910dae5be2de2955e9... [email protected] github.com Patch
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
ADP2026-02-19T21:03:33.363ZReported to Red Hat.
ADP2026-02-19T19:40:55.842ZMade public.

Solutions

ADP: RHSA-2026:7110: Red Hat Advanced Cluster Security for Kubernetes 4.8

ADP: RHSA-2026:7128: Red Hat Advanced Cluster Security for Kubernetes 4.9

ADP: RHSA-2026:6174: Red Hat Developer Hub 1.8

ADP: RHSA-2026:6802: Red Hat Developer Hub 1.9

Workarounds

ADP: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

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