CVE-2026-63466

Unleash is an open-source feature management platform. Prior to 8.0.3, FeatureEventFormatterMd.format in src/lib/addons/feature-event-formatter-md.ts assigns Mustache.escape to an identity function before rendering action and path templates. Because Mustache.escape is process-wide, the assignment disables escaping for subsequent Mustache.render calls in email-service.ts, webhook.ts, datadog.ts, and new-relic.ts. An editor-level user can place Slack or Microsoft Teams link syntax in an unrestricted username, trigger a feature event, and inject an attacker-labeled link into a trusted outbound notification channel, while other Mustache sinks remain unescaped until restart. This issue is fixed in version 8.0.3.

CVSS v3 4.1 MEDIUM

4.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.3 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction REQUIRED

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/Unleash/unleash/commit/002012cfdbedd2e9b7db9dc83b9f549f761db22e
https://github.com/Unleash/unleash/releases/tag/v8.0.3
https://github.com/Unleash/unleash/security/advisories/GHSA-w4mq-xh27-6xpx

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-21 19:17

Updated : 2026-09-09 21:20

NVD link : CVE-2026-63466

Mitre link : CVE-2026-63466

CVE.ORG link : CVE-2026-63466

JSON object : View

Products Affected

No product.

CWE

CWE-116

Improper Encoding or Escaping of Output

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