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.

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/vapor/leaf-kit/commit/8919e39476c3a4ba05c28b71546bb9195f87ef34	Patch
https://github.com/vapor/leaf-kit/security/advisories/GHSA-4hfh-fch3-5q7p	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:vapor:leafkit:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-02-20 22:16

Updated : 2026-03-02 13:34

NVD link : CVE-2026-27120

Mitre link : CVE-2026-27120

CVE.ORG link : CVE-2026-27120

JSON object : View

Products Affected

vapor

leafkit

CWE

CWE-75

Failure to Sanitize Special Elements into a Different Plane (Special Element Injection)

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CWE-87

Improper Neutralization of Alternate XSS Syntax

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