Novu: Stored XSS in In-App Inbox via notification redirect.url javascript: scheme (CVE-2026-75510) | HOL Guard CVE

Medium · CVSS 5.1CVE-2026-75510

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

Answer in brief

CVE-2026-75510 records a Medium severity (CVSS 5.1) vulnerability in Novu: Stored XSS in In-App Inbox via notification redirect.url javascript: scheme. The current sources do not mark it as known exploited. The current feed maps novuhq/novu (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 22, 2026Updated Sep 22, 2026Source checked Sep 22, 2026First seen by HOL Sep 22, 2026Material review Sep 22, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.1
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 5.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps novuhq/novu (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
novuhq/novugeneric	<3.18.0	3.18.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for novuhq/novu.
Review the reported fix. Update novuhq/novu to 3.18.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 22, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.