CVE-2026-28499

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 v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/vapor/leaf-kit/commit/6044b844caa858a0c5f2505ac166f5a057c990dc	Patch
https://github.com/vapor/leaf-kit/releases/tag/1.14.2	Release Notes
https://github.com/vapor/leaf-kit/security/advisories/GHSA-6jj5-j4j8-8473	Exploit Vendor Advisory
https://github.com/vapor/leaf-kit/security/advisories/GHSA-6jj5-j4j8-8473	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:vapor:leafkit:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-03-18 02:16

Updated : 2026-03-18 19:48

NVD link : CVE-2026-28499

Mitre link : CVE-2026-28499

CVE.ORG link : CVE-2026-28499

JSON object : View

Products Affected

vapor

leafkit

CWE

CWE-79

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CWE-80

Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)

CWE-116

Improper Encoding or Escaping of Output

{"id": "CVE-2026-28499", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "CHANGED", "version": "3.1", "baseScore": 6.1, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "LOW"}, "impactScore": 2.7, "exploitabilityScore": 2.8}], "cvssMetricV40": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 6.9, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "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", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "LOW", "vulnConfidentialityImpact": "NONE", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "published": "2026-03-18T02:16:24.060", "references": [{"url": "https://github.com/vapor/leaf-kit/commit/6044b844caa858a0c5f2505ac166f5a057c990dc", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/vapor/leaf-kit/releases/tag/1.14.2", "tags": ["Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/vapor/leaf-kit/security/advisories/GHSA-6jj5-j4j8-8473", "tags": ["Exploit", "Vendor Advisory"], "source": "security-advisories@github.com"}, {"url": "https://github.com/vapor/leaf-kit/security/advisories/GHSA-6jj5-j4j8-8473", "tags": ["Exploit", "Vendor Advisory"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-79"}, {"lang": "en", "value": "CWE-80"}, {"lang": "en", "value": "CWE-116"}]}], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "LeafKit es un lenguaje de plantillas con sintaxis inspirada en Swift. Antes de la versi\u00f3n 1.14.2, el escape de HTML no funciona correctamente cuando una plantilla imprime una colecci\u00f3n (Array / Dictionary) a trav\u00e9s de `#(value)`. Esto puede resultar en XSS, permitiendo que la entrada potencialmente no confiable se renderice sin escape. La versi\u00f3n 1.14.2 soluciona el problema."}], "lastModified": "2026-03-18T19:48:35.087", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:vapor:leafkit:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "C8687D7A-0F30-464E-8F28-21C4B1B29F0D", "versionEndExcluding": "1.14.2"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}