CVE-2026-27120
Leaf-kit html escaping does not work on characters that are part of extended grapheme cluster
CVSS Score
6.1
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-75 CWE-79 CWE-87 |
| Vendor | vapor |
| Product | leaf-kit |
| Published | Feb 20, 2026 |
| Last Updated | Feb 24, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
Affected Versions
vapor / leaf-kit
< 1.4.1