CVE-2026-28499

MEDIUM 6.1CVE-2026-28499 · Published 18/03/2026 · updated 17/06/2026

In short

CVE-2026-28499 is a MEDIUM (CVSS 6.1) vulnerability affecting leafkit (vapor).
Chance of exploitation in the next 30 days (EPSS): 0.28%, higher than 20.8% of all vulnerabilities.
Fix: update to 1.14.2 or later.

Package	Affected versions	Patched versions
leafkit vapor	`< 1.14.2`	`1.14.2`

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.

References

vapor/leaf-kit commit 6044b84 · Patch
vapor/leaf-kit release 1.14.2 · Release Notes
vapor/leaf-kit security advisory · Exploit

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