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CVE-2026-28499

23
FAUCET Score

CVE-2026-28499 describes a Cross-Site Scripting (XSS) vulnerability in the LeafKit templating language, affecting versions prior to 1.14.2. The flaw stems from incorrect HTML escaping when printing collections (Arrays/Dictionaries), allowing potentially untrusted input to be rendered unescaped. This vulnerability is rated Medium severity (CVSS 6.1), with a network attack vector, low complexity, and requiring user interaction for exploitation. Currently, there is no evidence of active exploitation, public exploit code, or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.14.2CPE matchmatch criteria
cpe:2.3:a:vapor:leafkit:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

6.9MEDIUM

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
VS Confidentiality
NONE
VS Integrity
NONE
VS Availability
NONE
SS Confidentiality
LOW
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.27%
Probability of exploitation in next 30 days
EPSS Percentile
18.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0027 is in the 19th percentile among its peer group of 26,221 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

swiftpatch availablevia ghsa
Product: github.com/vapor/leaf-kitFixed in: 1.14.2

Vendor Advisories (1)

swiftGHSA-6jj5-j4j8-8473medium

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

Mar 16, 2026

References

github.com / vapor/leaf-kit/commit/6044b844caa858a0c5f2505ac166f5a057c990dc
Patch
github.com / vapor/leaf-kit/releases/tag/1.14.2
Release Notes
github.com / vapor/leaf-kit/security/advisories/GHSA-6jj5-j4j8-8473
ExploitVendor Advisory