# CVE-2026-75510: Novu: Stored XSS in In-App Inbox via notification redirect.url javascript: scheme

> An attacker can inject JavaScript into notification redirects, allowing session theft and authenticated actions when users click notifications in the inbox.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 22 Sep 2026
- **Updated:** 22 Sep 2026
- **Also known as:** GHSA-8gr3-5j6f-25gp

## What is CVE-2026-75510?

CVE-2026-75510 is a medium-severity cross-site scripting vulnerability in novuhq novu, published on 22 Sep 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Novu provides an API for sending notifications through multiple channels. Prior to 3.18.0, Novu's @novu/js In-App Inbox and the @novu/react Inbox component accept a notification call-to-action redirect.url from the v1 cta.data object and pass it through apps/api/src/app/inbox/utils/notification-mapper.ts and packages/js/src/ui/components/Notification/DefaultNotification.tsx to the navigate function in packages/js/src/ui/context/InboxContext.tsx without validating its URL scheme. An authenticated organization member or environment API-key holder can store a javascript: redirect with target _self in an in-app workflow. When a recipient using a Chromium-based browser clicks the notification, window.open executes the redirect in the current inbox-hosting origin, which can expose session material and permit authenticated actions in a customer application or the self-hosted Novu dashboard. This issue is fixed in version 3.18.0.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-75510?

2 open source packages ship an affected version, including @novu/js.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@novu/js` | npm | All versions | 3.18.0 |
| `@novu/js` | npm | All versions | 3.18.0 |

## How do I fix CVE-2026-75510?

Upgrade @novu/js to 3.18.0 or later.

## Is CVE-2026-75510 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-75510 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-75510 and fix it if it is affected.

What it is: CVE-2026-75510 is a medium-severity cross-site scripting vulnerability in novuhq novu, published on 22 Sep 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-75510 exists.

Affected packages and fixed versions:
- @novu/js (npm): affected all versions; fixed in 3.18.0
- @novu/js (npm): affected all versions; fixed in 3.18.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-75510/ (Markdown: https://insights.sbomify.com/CVE-2026-75510/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-75510
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-75510
- OSV: https://osv.dev/vulnerability/CVE-2026-75510

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-75510/
Summaries are generated and may contain mistakes; the official description above is the record.