# CVE-2024-56136: /api/v1/jwt/fetch_api_key endpoint can leak if an email address has an account in Zulip server

> Unauthenticated attackers can determine if an email address is registered on multi-organization Zulip servers, leaking user account existence.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Jan 2025
- **Updated:** 6 Feb 2025
- **Also known as:** GHSA-5xg8-xhfj-4hm6

## What is CVE-2024-56136?

CVE-2024-56136 is a medium-severity vulnerability in zulip, published on 16 Jan 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Zulip server provides an open-source team chat that helps teams stay productive and focused. Zulip Server 7.0 and above are vulnerable to an information disclose attack, where, if a Zulip server is hosting multiple organizations, an unauthenticated user can make a request and determine if an email address is in use by a user. Zulip Server 9.4 resolves the issue, as does the `main` branch of Zulip Server. Users are advised to upgrade. There are no known workarounds for this issue.

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2024-56136?

It affects 1 product.


Products: Zulip Zulip Server.

## How do I fix CVE-2024-56136?

No fix has been published for CVE-2024-56136 yet. Limit exposure of the affected software until one is available.

## Is CVE-2024-56136 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-56136 exists.

## Other vulnerabilities in zulip

- [CVE-2019-18933](https://insights.sbomify.com/CVE-2019-18933/): Information disclosure in n/a (critical 9.8)
- [CVE-2020-15070](https://insights.sbomify.com/CVE-2020-15070/): Code injection in n/a (high 8.8)
- [CVE-2017-0910](https://insights.sbomify.com/CVE-2017-0910/): Missing authorization in Zulip Server (high 8.8)
- [CVE-2025-31478](https://insights.sbomify.com/CVE-2025-31478/): Zulip Authentication Backend Configuration Bypass (high 8.2)
- [CVE-2023-33186](https://insights.sbomify.com/CVE-2023-33186/): Cross-site scripting vulnerability in Zulip Server development branch via topic tooltip (high 8.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-56136 and fix it if it is affected.

What it is: CVE-2024-56136 is a medium-severity vulnerability in zulip, published on 16 Jan 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2024-56136 exists.

Affected product: zulip. 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-2024-56136/ (Markdown: https://insights.sbomify.com/CVE-2024-56136/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-56136
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-56136
- OSV: https://osv.dev/vulnerability/CVE-2024-56136

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-56136/
Summaries are generated and may contain mistakes; the official description above is the record.