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HIGH

CVE-2026-26278

CVSS v3

7.5

HIGH

EPSS Score

1.1 %

exploit probability, as of 2026-10-17

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • fast-xml-parsernpmfrom 5.0.0 · fixed in 5.3.6

Vendor advisories

  • CVE-2026-26278 Red Hat Product Security245 products fixed · 6 known affected

    fast-xml-parser: fast-xml-parser: Denial of Service via unlimited XML entity expansion

    mta/mta-ui-rhel9 as a component of Migration Toolkit for Applications 8 · openshift-gitops-1/argocd-rhel8 as a component of Red Hat OpenShift GitOps · openshift-gitops-1/argocd-rhel9 as a component of Red Hat OpenShift GitOps

  • RHSA-2026:51349 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: General availability of the satellite/iop-host-inventory-frontend-rhel9 container image

  • RHSA-2026:41944 Red Hat Product Security78 products fixed

    Red Hat Security Advisory: Red Hat OpenShift Data Foundation 4.19.20 security, enhancement & bug fix update

  • RHSA-2026:41941 Red Hat Product Security68 products fixed

    Red Hat Security Advisory: Red Hat OpenShift Data Foundation 4.18.25 security, enhancement & bug fix update

  • RHSA-2026:40984 Red Hat Product Security88 products fixed

    Red Hat Security Advisory: Red Hat OpenShift Data Foundation 4.20.15 security, enhancement & bug fix update

  • RHSA-2026:7128 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: RHACS 4.9.5 security and bug fix update

3 more advisories

Full record on NVD

Description

fast-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.

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2026-02-19
Last Modified
2026-02-23

Frequently asked questions

What is CVE-2026-26278?

fast-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.

Is CVE-2026-26278 actively exploited?

Active exploitation of CVE-2026-26278 has not been confirmed. Its EPSS score was 1.1% on 2026-10-17, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-26278?

CVE-2026-26278 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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