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

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

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A: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:** No
- **Published:** 24 Mar 2026
- **Updated:** 24 Mar 2026
- **Also known as:** GHSA-p6v5-227f-f3fv

## 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 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-33400?

It affects 1 product.


Products: 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.

## Is CVE-2026-33400 being exploited?

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

## Other vulnerabilities in ellite Wallos

- [CVE-2024-55371](https://insights.sbomify.com/CVE-2024-55371/): File upload in n/a (critical 9.8)
- [CVE-2024-55372](https://insights.sbomify.com/CVE-2024-55372/): File upload in n/a (critical 9.8)
- [CVE-2026-30840](https://insights.sbomify.com/CVE-2026-30840/): Wallos: Server-Side Request Forgery (SSRF) in Notification Testers (high 8.8)
- [CVE-2026-30828](https://insights.sbomify.com/CVE-2026-30828/): Wallos: SSRF via url parameter leading to File Traversal (high 8.7)
- [CVE-2026-33407](https://insights.sbomify.com/CVE-2026-33407/): Wallos: SSRF via HTTP Proxy Environment Variable (high 8.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33400 and fix it if it is affected.

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

Affected product: ellite Wallos. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-33400/ (Markdown: https://insights.sbomify.com/CVE-2026-33400/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33400
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33400
- OSV: https://osv.dev/vulnerability/CVE-2026-33400

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33400/
Summaries are generated and may contain mistakes; the official description above is the record.