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CVE-2026-28499

LeafKit's HTML escaping may be skipped for Collection values, enabling XSS

Published: Mar 18, 2026Updated: Mar 18, 2026 Sources: CVE List NVD GHSACWE-79
NVD MITRE
6.1CVSSMEDIUM
EPSS Score
0.3%
Top 82.4%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:RS:CC:LI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:RUser Interaction
Required
Scope
S:CScope
Changed
Impact
C:LConfidentiality
Low
I:LIntegrity
Low
A:NAvailability
None
Open in CVSS calculator →

Weaknesses

CWE-79CWE-80CWE-116

Affected Products

leafkitvapor
Mixed
OSS Libraries / web-framework
leaf-kitvapor
Mixed
OSS Libraries / web-framework
github.com/vapor/leaf-kitSwiftURL
Library
OSS Libraries / generic-library
vapoross-projectOSS Librariesaka vapor swift framework
swifturlOSS Librariesaka swift-nio-http2, github.com/vapor/vapor, github.com/pytorch/executorch, swift-nio-http2, github.com/apple/swift-nio-http2

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Execution
Initial Access
View detailed technique mapping

References

https://github.com/vapor/leaf-kit/commit/6044b844caa858a0c5f2505ac166f5a057c990dc
github.com
https://github.com/vapor/leaf-kit/releases/tag/1.14.2
github.com
https://github.com/vapor/leaf-kit/security/advisories/GHSA-6jj5-j4j8-8473
github.com
and 2 more references View all →

Timeline

Published
Mar 18, 2026
Last Updated
Mar 18, 2026

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