CVE-2026-9520 blitz-js blitz Sign-in LoginForm.tsx cross site scripting
Cross-site scripting in Blitz.js sign-in form allows remote attackers to inject scripts, potentially leading to session hijacking or code execution.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-9520?
CVE-2026-9520 is a medium-severity cross-site scripting vulnerability in blitz-js blitz, published on 26 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
A weakness has been identified in blitz-js blitz up to 3.0.2 on GitHub. This impacts an unknown function of the file packages/generator/templates/app/src/app/auth/components/LoginForm.tsx of the component Sign-in. This manipulation of the argument Next causes cross site scripting. It is possible to initiate the attack remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.
Which versions are affected by CVE-2026-9520?
2 open source packages ship an affected version, including blitz.
| Package | Affected | Fixed in |
|---|---|---|
blitz npm | All versions to 3.0.2 | None |
blitz npm | All versions to 3.0.2 | None |
How do I fix CVE-2026-9520?
No fix has been published for CVE-2026-9520 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-9520 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-9520 exists.
Sources
Also known as GHSA-h2p9-cr4h-px24.