Home/CVE/LeafKit is a templating language with Swift-inspired syntax. Prior to version 1.14.2, HTML escaping doesn't work correct
CVE

CVE-2026-28499

LeafKit is a templating language with Swift-inspired syntax. Prior to version 1.14.2, HTML escaping doesn't work correct

LeafKit is a templating language with Swift-inspired syntax. Prior to version 1.14.2, HTML escaping doesn't work correctly when a template prints a collection (Array / Dictionary) via #(value). This can result in XSS, allowing potentially untrusted input to be rendered unescaped.

Version 1.14.2 fixes the issue.

MEDIUM · CVSS 6.1 EPSS 0.00017
Schedule remediation
  • Public exploit or PoC is available
  • SSVC automatable: yes - attacks can be scripted at scale
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-116Improper Encoding or Escaping of Output
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
▤

Affected Products & Versions

1
vapor leafkit< 1.14.2
▤

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 1.14.2
⚠

Public Exploits & PoCs

1
pocgithub.com · GHSA-6jj5-j4j8-8473github.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 NVD18 Mar 2026 · 02:16 AM
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
yes
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

2
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/6044b844caa858a0c5f2505ac166f5a057c990dcPatch
https://github.com/vapor/leaf-kit/releases/tag/1.14.2Release Notes
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