# CVE-2023-47642: Stream description leaks to ex-subscribers in Zulip

> Former stream subscribers can access restricted stream metadata, including names and settings, due to improper access control checks.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Nov 2023
- **Updated:** 29 Aug 2024
- **Also known as:** GHSA-c9wc-65fh-9x8p

## What is CVE-2023-47642?

CVE-2023-47642 is a medium-severity vulnerability in zulip, published on 16 Nov 2023. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Zulip is an open-source team collaboration tool. It was discovered by the Zulip development team that active users who had previously been subscribed to a stream incorrectly continued being able to use the Zulip API to access metadata for that stream. As a result, users who had been removed from a stream, but still had an account in the organization, could still view metadata for that stream (including the stream name, description, settings, and an email address used to send emails into the stream via the incoming email integration). This potentially allowed users to see changes to a stream’s metadata after they had lost access to the stream. This vulnerability has been addressed in version 7.5 and all 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-2023-47642?

It affects 1 product.


Products: Zulip Zulip Server.

## How do I fix CVE-2023-47642?

No fix has been published for CVE-2023-47642 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-47642 being exploited?

There is no known exploitation of CVE-2023-47642 in the wild and no public exploit code.

## 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-2023-47642 and fix it if it is affected.

What it is: CVE-2023-47642 is a medium-severity vulnerability in zulip, published on 16 Nov 2023. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-47642 in the wild and no public exploit code.

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-2023-47642/ (Markdown: https://insights.sbomify.com/CVE-2023-47642/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-47642
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-47642
- OSV: https://osv.dev/vulnerability/CVE-2023-47642

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-47642/
Summaries are generated and may contain mistakes; the official description above is the record.