CVE-2026-76909: Unleash: CR-approval email renders user-controlled raw HTML
Summary The change-request approval HTML email template renders fields as raw HTML. User who can create a change request can inject HTML into approval notification emails. I was not able to confirm Enterprise platform is using vulnerable code nor that it doesn't sanitize input.
Details src/mailtemplates/requested-cr-approval/requested-cr-approval.html.mustache uses Mustache triple-stash syntax for fields that can originate from users:
mustache {{{ changeRequestTitle }}} {{{ requesterName }}} {{{ requesterEmail }}} {{{ changeRequestLink }}}
Triple-stash disables HTML escaping even when Mustache's global escape function is safe. The related renderer is sendRequestedCRApprovalEmail in src/lib/services/email-service.ts, which renders the template with Mustache.render.
PoC 1. Use an Enterprise deployment with change requests and approval emails enabled. 2. As a project member who can create change requests, set a display name or change-request title to HTML such as:
html </a><a href="https://example.com">Approve change request</a>
3. Create a change request that requires approval. 4. Observe that the approval email contains attacker-controlled raw HTML instead of escaped text.
Impact Change-request approvers can receive forged links, tracking pixels, or visually altered email content.
Other sources
Unleash is an open-source feature management platform. Prior to 8.0.3, the change-request approval email template at src/mailtemplates/requested-cr-approval/requested-cr-approval.html.mustache renders the user-controlled changeRequestTitle, requesterName, and requesterEmail values without HTML escaping, and sendRequestedCRApprovalEmail passes those values to Mustache rendering. A project member who can create a change request when approval emails are enabled can inject HTML into an approver's notification, allowing forged links, tracking content, or visually altered email content. This issue is fixed in version 8.0.3.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
npm/unleash-serverto a version that resolves this vulnerability.Fixed in 8.0.3 - Upgrade
Upgrade
Unleashto a version that resolves this vulnerability.Fixed in 8.0.3
Event History
Frequently Asked Questions
Who can exploit this issue?
A project member who can create a change request can supply the affected values. Exploitation also requires change-request approval emails to be enabled and an approver to receive the notification.
Which recipients are exposed to the malicious content?
Approvers receiving change-request approval notification emails are exposed. The injected content can include forged links, tracking content, or visually altered email content.
What should teams do if they cannot immediately upgrade?
Disable change-request approval emails if possible, or restrict change-request creation to trusted project members until the instance can be upgraded. The issue is fixed in version 8.0.3.