Emissary has Stored XSS via Navigation Template Link Injection

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.8 · CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

EPSS

• CVE-2026-35571: 0.18% estimated exploitation activity in the next 30 days; percentile 7.08 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary 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. Details Vulnerable code — nav.mustache (line 10) The {{link}} value was rendered without any scheme validation. Mustache's default HTML escaping protects against injection of new HTML tags but does not prevent javascript: URIs in href attributes, since javascript: contains no characters that HTML-escaping would alter. Attack vector An administrator sets a navigation item's link to: Any authenticated user who clicks the navigation link executes the script in their browser context. Impact - Session hijacking via cookie theft - Actions performed on behalf of the victim user - Requires administrative access to modify navigation…

Published by the source

7 Apr 2026, 20:17 UTC

Last modified by the source

4 Nov 2026, 22:07 UTC

Source last checked

4 Nov 2026, 22:30 UTC

1. Revision 2 · amended · 4 Nov 2026

   Amended from ghsa record GHSA-cpm7-cfpx-3hvp

2. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-cpm7-cfpx-3hvp

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# Patch Next advisory brief: CVE-2026-35571

Advisory: Emissary has Stored XSS via Navigation Template Link Injection
IDs: CVE-2026-35571, GHSA-cpm7-cfpx-3hvp
Record: https://patchnext.com/advisories/cve-2026-35571 (revision 2, source checked 4 Nov 2026, 22:30 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: gov.nsa.emissary:emissary 8.39.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven gov.nsa.emissary:emissary: affected <= 8.38.0; fixed in 8.39.0

## Suggested inspection (read-only)
- Maven gov.nsa.emissary:emissary: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on gov.nsa.emissary:emissary.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-cpm7-cfpx-3hvp (GitHub-reviewed advisory GHSA-cpm7-cfpx-3hvp lists affected ranges: Maven gov.nsa.emissary:emissary >=0 <=8.38.0)

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