CVE-2026-35571: Emissary has Stored XSS via Navigation Template Link Injection

Severity: medium (CVSS 4.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-07 · updated 2026-10-26
Weakness: CWE-79

Description

Emissary is a P2P based data-driven workflow engine. Prior to 8.39.0, Mustache navigation templates interpolated configuration-controlled link values directly into href attributes without URL scheme validation. An administrator who could modify the navItems configuration could inject javascript: URIs, enabling stored cross-site scripting (XSS) against other authenticated users viewing the Emissary web interface. This vulnerability is fixed in 8.39.0.

Affected products

NationalSecurityAgency emissary: through 8.38.0

References

https://github.com/NationalSecurityAgency/emissary/pull/1293
https://github.com/NationalSecurityAgency/emissary/security/advisories/GHSA-cpm7-cfpx-3hvp

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