Leafkit is a templating language with Swift-inspired syntax. Prior to 1.4.1, htmlEscaped in leaf-kit will only escape html special characters if the extended grapheme clusters match, which allows bypassing escaping by using an extended grapheme cluster containing both the special html character and some additional characters. In the case of html attributes, this can lead to XSS if there is a leaf variable in the attribute that is user controlled. This vulnerability is fixed in 1.4.1.
History

Fri, 20 Feb 2026 21:45:00 +0000

Type Values Removed Values Added
Description Leafkit is a templating language with Swift-inspired syntax. Prior to 1.4.1, htmlEscaped in leaf-kit will only escape html special characters if the extended grapheme clusters match, which allows bypassing escaping by using an extended grapheme cluster containing both the special html character and some additional characters. In the case of html attributes, this can lead to XSS if there is a leaf variable in the attribute that is user controlled. This vulnerability is fixed in 1.4.1.
Title Leaf-kit html escaping does not work on characters that are part of extended grapheme cluster
Weaknesses CWE-75
CWE-79
CWE-87
References
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-02-20T21:27:09.642Z

Reserved: 2026-02-17T18:42:27.043Z

Link: CVE-2026-27120

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-02-20T22:16:29.830

Modified: 2026-02-20T22:16:29.830

Link: CVE-2026-27120

cve-icon Redhat

No data.