CVE-2026-76909: Unleash change-request approval email HTML injection

CVE-2026-76909 · Severity: medium · CVSS 4 · Published 2026-09-22

Unleash is a feature management and experimentation platform that supports change requests requiring approval from designated reviewers. A vulnerability in the approval notification email template allows users who can create change requests to inject arbitrary HTML into emails sent to approvers. This can be exploited to display forged approval links, redirect approvers to malicious sites, inject tracking pixels, or manipulate email content to deceive recipients.

Technologies: unleash-server (npm). Vendors: npm.

Quick answers

Is CVE-2026-76909 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-76909 being exploited in the wild.
How severe is CVE-2026-76909?
Medium severity, with a CVSS score of 4, published 22 September 2026.
Which products and versions are affected?
unleash-server (npm) < 8.0.3, SEMVER:introduced=0,fixed=8.0.3.
Is there a fix for CVE-2026-76909?
Yes. unleash-server (npm): upgrade to 8.0.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-76909 attacked?
It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-76909?
Check whether you run unleash-server (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • unleash-server (npm): upgrade to 8.0.3 or later
    npm install unleash-server@8.0.3

Technical details

The vulnerability is a cross-site scripting (XSS) flaw in the change-request approval email template (requested-cr-approval.html.mustache). The template uses Mustache triple-brace syntax ({{{ }}} ) to render user-controlled fields such as changeRequestTitle, requesterName, requesterEmail, and changeRequestLink without HTML escaping. The sendRequestedCRApprovalEmail function in email-service.ts uses Mustache.render to process the template. An attacker with change-request creation privileges can set their display name or the change-request title to contain HTML/JavaScript, which will be rendered raw in approval emails sent to reviewers. No user interaction beyond normal workflow (creating a change request) is required to trigger the vulnerability. The patch is available in version 8.0.3 and later.

Affected products

  • Unleash unleash-server < 8.0.3

Identifiers

  • CVE-2026-76909
  • GHSA-7hvx-28gp-mf6j

Timeline

  • 2026-07-10: disclosed
  • 2026-09-22: advisory
  • 2026-09-22: patched: Version 8.0.3 released

References

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