# CVE-2026-26278

## Summary

- **CVE ID:** CVE-2026-26278
- **Severity:** HIGH
- **CVSS Score:** 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** CWE-776
- **Published:** Feb 19, 2026
- **Last Modified:** Sep 10, 2026

## 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.

## Affected Products

- NaturalIntelligence — fast-xml-parser (>= 5.0.0, < 5.3.6)
- NaturalIntelligence — fast-xml-parser (>= 4.1.3, < 4.5.4)

## References

- [CNA](https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-jmr7-xgp7-cmfj)
- [CNA](https://github.com/NaturalIntelligence/fast-xml-parser/commit/910dae5be2de2955e968558fadf6e8f74f117a77)
- [CNA](https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.3.6)
- [GitHub](https://github.com/advisories/GHSA-jmr7-xgp7-cmfj)
- [redhat-SADP](https://access.redhat.com/security/cve/CVE-2026-26278)
- [redhat-SADP](https://bugzilla.redhat.com/show_bug.cgi?id=2441120)
- [redhat-SADP](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-26278.json)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:7110)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:7128)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:6174)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:6802)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:40984)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:41941)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:41944)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:51349)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.84%
- **EPSS Percentile:** 55.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._