VulnerabilityModified

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.

HIGH 7.5EPSS 0.84%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.84%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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.

CVSS 3.1: 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.84% probability · 56th percentile
CISA KEV: Not listed
Weakness: CWE-776
Affected: naturalintelligence/fast-xml-parser
Source: security-advisories@github.com

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.