Medium 6.9Published Mar 17, 2026

CVE-2026-28499LeafKit's HTML escaping may be skipped for Collection values, enabling XSS

Updated under an hour ago (Oct 27, 2026, 7:10 AM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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: 6.9 MEDIUM (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N
Weakness (CWE): CWE-79, CWE-80, CWE-116
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Mar 18, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

vapor leaf-kit vapor:leaf_kit (from the name)	before 1.14.2	CNA record
vapor leafkit vapor:leafkit	before 1.14.2	NVD

References

References

https://github.com/vapor/leaf-kit/security/advisories/GHSA-6jj5-j4j8-8473	x-refsource-confirm, exploit, vendor-advisory
https://github.com/vapor/leaf-kit/commit/6044b844caa858a0c5f2505ac166f5a057c990dc	x-refsource-misc, patch
https://github.com/vapor/leaf-kit/releases/tag/1.14.2	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.