# CVE-2026-34721: Zammad has Cross-site request forgery (CSRF) in OAuth callback endpoints

> Attackers can exploit missing CSRF validation in OAuth callbacks to hijack user accounts in Zammad helpdesk systems.

- **Severity:** Medium 5.9 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:L/VI:H/VA:N/SC:N/SI:N/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:** No
- **Published:** 8 Apr 2026
- **Updated:** 9 Apr 2026
- **Also known as:** GHSA-mfwp-hx66-626c

## What is CVE-2026-34721?

CVE-2026-34721 is a medium-severity vulnerability in Zammad Zammad, published on 8 Apr 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

Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.1 and 6.5.4, the OAuth callback endpoints for Microsoft, Google, and Facebook external credentials do not validate a CSRF state parameter. This vulnerability is fixed in 7.0.1 and 6.5.4.

Weakness: CWE-352 (Cross-Site Request Forgery)

## Which versions are affected by CVE-2026-34721?

It affects 1 product.


Products: Zammad Zammad.

## How do I fix CVE-2026-34721?

No fix has been published for CVE-2026-34721 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-34721 being exploited?

There is no known exploitation of CVE-2026-34721 in the wild and no public exploit code.

## Other vulnerabilities in Zammad Zammad

- [CVE-2026-102489](https://insights.sbomify.com/CVE-2026-102489/): Zammad GmbH Zammad Session Fixation (high 8.7, exploited in the wild)
- [CVE-2026-102490](https://insights.sbomify.com/CVE-2026-102490/): Zammad GmbH Zammad Improper Privilege Management (high 8.5, exploited in the wild)
- [CVE-2022-48021](https://insights.sbomify.com/CVE-2022-48021/): Code injection in n/a (critical 9.8)
- [CVE-2022-35490](https://insights.sbomify.com/CVE-2022-35490/): Security feature bypass in n/a (critical 9.8)
- [CVE-2021-42090](https://insights.sbomify.com/CVE-2021-42090/): Deserialization in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34721 and fix it if it is affected.

What it is: CVE-2026-34721 is a medium-severity vulnerability in Zammad Zammad, published on 8 Apr 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-34721 in the wild and no public exploit code.

Affected product: Zammad Zammad. 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-2026-34721/ (Markdown: https://insights.sbomify.com/CVE-2026-34721/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34721
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34721
- OSV: https://osv.dev/vulnerability/CVE-2026-34721

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34721/
Summaries are generated and may contain mistakes; the official description above is the record.