fast-xml-builder Comment Value regex can be bypassed
Date: 2026-05
Affected: npm/fast-xml-builder
Attack vector: other
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2026-41650
CVE-2026-44664
CWE: CWE-91
CVSS: 6.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)

# Summary The fix for https://github.com/advisories/GHSA-gh4j-gqv2-49f6 in fast-xml-parser sanitizes `--` sequences in XML comment content using .replace(/--/g, '- -'). This skip the values containing three consecutive dashes (e.g., --->...), allowing an attacker to break out of an XML comment and inject arbitrary XML/HTML content. ### Impact Any application with comment property enabled allow attacker to inject malicious or unwanted code like JS script tag in the XML/HTML output. ### Workarounds Check for the presence of 3 consecutive dashes externally in the property value used for comment tag.


Mitigations:

Architectural layers (MAESTRO):