# CVE-2017-0910: Missing authorization in Zulip Server

> An authorized user in one realm can create accounts in other realms on multi-realm Zulip servers, enabling unauthorized access and privilege escalation.

- **Severity:** High 8.8 (`CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 27 Nov 2017
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-6r66-34x7-46rg

## What is CVE-2017-0910?

CVE-2017-0910 is a high-severity missing authorization vulnerability in Zulip Server, published on 27 Nov 2017. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

In Zulip Server before 1.7.1, on a server with multiple realms, a vulnerability in the invitation system lets an authorized user of one realm on the server create a user account on any other realm.

Weakness: CWE-287 (Improper Authentication), CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2017-0910?

It affects 1 product.


Products: Zulip Zulip Server.

## How do I fix CVE-2017-0910?

No fix has been published for CVE-2017-0910 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-0910 being exploited?

There is no known exploitation of CVE-2017-0910 in the wild and no public exploit code.

## Other vulnerabilities in Zulip Server

- [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-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)
- [CVE-2024-36612](https://insights.sbomify.com/CVE-2024-36612/): Denial of service in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-0910 and fix it if it is affected.

What it is: CVE-2017-0910 is a high-severity missing authorization vulnerability in Zulip Server, published on 27 Nov 2017. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2017-0910 in the wild and no public exploit code.

Affected product: Zulip Server. 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-2017-0910/ (Markdown: https://insights.sbomify.com/CVE-2017-0910/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-0910
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-0910
- OSV: https://osv.dev/vulnerability/CVE-2017-0910

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-0910/
Summaries are generated and may contain mistakes; the official description above is the record.