Home/CVE/Leafkit is a templating language with Swift-inspired syntax. Prior to 1.4.1, htmlEscaped in leaf-kit will only escape ht
CVE

CVE-2026-27120

Leafkit is a templating language with Swift-inspired syntax. Prior to 1.4.1, htmlEscaped in leaf-kit will only escape ht

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.

MEDIUM · CVSS 6.1 EPSS 0.00017
Schedule remediation
  • Public exploit or PoC is available
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-75Failure to Sanitize Special Elements into a Different Plane (Special Element Injection)
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-87Improper Neutralization of Alternate XSS Syntax
▤

Affected Products & Versions

1
vapor leafkit< 1.14.1
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
SwiftURL github.com/vapor/leaf-kit MEDIUM fixed in 1.4.1
⚠

Public Exploits & PoCs

1
pocgithub.com · GHSA-4hfh-fch3-5q7pgithub.com
▣

Scoring & Timeline

6.1
MEDIUM · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD20 Feb 2026 · 10:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
SSVC triage · cisa-vulnrichment
Exploitation
poc
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/vapor/leaf-kit/commit/8919e39476c3a4ba05c28b71546bb9195f87ef34Patch
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