CVE-2026-33400 Wallos: Stored cross-site scripting (XSS) vulnerability in the payment method rename endpoint

Medium 5.4 Published 24 Mar 2026 Updated 24 Mar 2026

Authenticated users can inject JavaScript via payment method renaming, leading to session hijacking when others view specific pages.

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: None listed

What is CVE-2026-33400?

CVE-2026-33400 is a medium-severity cross-site scripting vulnerability in ellite Wallos, published on 24 Mar 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

Wallos is an open-source, self-hostable personal subscription tracker. Prior to version 4.7.0, a stored cross-site scripting (XSS) vulnerability in the payment method rename endpoint allows any authenticated user to inject arbitrary JavaScript that executes when any user visits the Settings, Subscriptions, or Statistics pages. Combined with the wallos_login authentication cookie lacking the HttpOnly flag, this enables full session hijacking. This issue has been patched in version 4.7.0.

Weakness: CWE-79

Which versions are affected by CVE-2026-33400?

It affects 1 product.

Products include Wallosapp Wallos.

How do I fix CVE-2026-33400?

No fix has been published for CVE-2026-33400 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-2026-33400 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33400 exists.

Sources

Also known as GHSA-p6v5-227f-f3fv.