CVE-2026-27120

MEDIUM

6.1

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.

CVE Details

CVSS v3.1 Score6.1

SeverityMEDIUM

CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionREQUIRED

Published2/20/2026

Last Modified3/2/2026

Sourcenvd

Honeypot Sightings0

Affected Products

vapor:leafkit

Weaknesses (CWE)

CWE-75CWE-79CWE-87

References

https://github.com/vapor/leaf-kit/commit/8919e39476c3a4ba05c28b71546bb9195f87ef34(security-advisories@github.com)

https://github.com/vapor/leaf-kit/security/advisories/GHSA-4hfh-fch3-5q7p(security-advisories@github.com)

IOC Correlations

No correlations recorded

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