CVE-2026-75510: Novu stored XSS in In-App Inbox via javascript: scheme in redirect URL

CVE-2026-75510 · Severity: medium · CVSS 4 · Published 2026-09-22

Novu is a notification and inbox service that allows organizations to send and manage in-app notifications to users. A low-privilege workflow author can inject malicious JavaScript into notifications that executes in the browser of any recipient who clicks the notification, potentially allowing theft of session tokens, authentication cookies, or execution of actions on behalf of the victim in the application's origin.

Technologies: Novu. Vendors: Novu, npm.

Quick answers

Is CVE-2026-75510 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-75510 being exploited in the wild.
How severe is CVE-2026-75510?
Medium severity, with a CVSS score of 4, published 22 September 2026.
Which products and versions are affected?
Novu @Novu/React <= 3.15.0; Novu API <= 3.15.0; @novu/js (npm) <= 3.17.0, SEMVER:introduced=0,fixed=3.18.0.
Is there a fix for CVE-2026-75510?
Yes. @novu/js (npm): upgrade to 3.18.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-75510 attacked?
It is attacked over the network, in a web application.
Am I affected by CVE-2026-75510?
Check whether you run Novu @Novu/React, Novu or @novu/js (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

  • @novu/js (npm): upgrade to 3.18.0 or later
    npm install @novu/js@3.18.0

Technical details

The vulnerability is a stored cross-site scripting (XSS) flaw in the `@novu/js` In-App Inbox renderer. The `navigate()` function in the notification click handler passes a notification's `redirect.url` to `window.open()` without validating the URL scheme, allowing `javascript:` URLs to be executed. A workflow author (authenticated) can craft a v1 in-app workflow with a CTA containing `url: "javascript:<payload>"` and `target: "_self"`. The server-side notification mapper copies these values without scheme validation (v2 schema does validate via `redirectUrlRegex`, but v1 does not), and the client renderer invokes `window.open(url, "_self", "noopener,noreferrer")`. In Chromium browsers, `javascript:` URLs opened with `target="_self"` execute in the current document origin. The attack requires an authenticated workflow author and a Chromium-based browser on the victim side; victims of the self-hosted dashboard can have their session tokens exfiltrated from `localStorage['self-hosted-jwt']` and used to impersonate other members or admins.

Affected products

  • Novu Novu API <= 3.15.0
  • Novu @novu/js <= 3.15.0
  • Novu @novu/react <= 3.15.0

Identifiers

  • CVE-2026-75510
  • GHSA-8gr3-5j6f-25gp

Timeline

  • 2026-09-22: disclosed: Advisory published

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