CVE-2026-27120

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.

Scoring

Severity
MEDIUM
CVSS base score
6.1
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS probability
0.23%
CWE
CWE-75, CWE-79, CWE-87
Published
2026-02-20
Last modified
2026-03-12

Affected products

Weakness type

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