# CVE-2021-32689: Nextcloud Talk not properly disassociating users from chats after account deletion

> Attackers can read previous users' chat messages by reusing deleted usernames if self-registration is enabled.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 12 Jul 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-xv6f-344w-895c

## What is CVE-2021-32689?

CVE-2021-32689 is a high-severity missing authorization vulnerability in nextcloud security-advisories, published on 12 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Nextcloud Talk is a fully on-premises audio/video and chat communication service. In versions prior to 11.2.2, if a user was able to reuse an earlier used username, they could get access to any chat message sent to the previous user with this username. The issue was patched in versions 11.2.2 and 11.3.0. As a workaround, don't allow users to choose usernames themselves. This is the default behaviour of Nextcloud, but some user providers may allow doing so.

Weakness: CWE-708 (Incorrect Ownership Assignment), CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2021-32689?

It affects 1 product.


Products: Nextcloud Talk.

## How do I fix CVE-2021-32689?

No fix has been published for CVE-2021-32689 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-32689 being exploited?

There is no known exploitation of CVE-2021-32689 in the wild and no public exploit code.

## Other vulnerabilities in nextcloud security-advisories

- [CVE-2020-8180](https://insights.sbomify.com/CVE-2020-8180/): Code injection in Nextcloud Talk (critical 9.9)
- [CVE-2023-39957](https://insights.sbomify.com/CVE-2023-39957/): Path traversal allows tricking the Talk Android app into writing files into it's root directory (high 7.2)
- [CVE-2021-32676](https://insights.sbomify.com/CVE-2021-32676/): Session Fixation in Nextcloud Talk (medium 6.5)
- [CVE-2021-39222](https://insights.sbomify.com/CVE-2021-39222/): XSS in Talk (medium 6.4)
- [CVE-2018-3781](https://insights.sbomify.com/CVE-2018-3781/): Cross-site scripting in nextcloud/talk (medium 5.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32689 and fix it if it is affected.

What it is: CVE-2021-32689 is a high-severity missing authorization vulnerability in nextcloud security-advisories, published on 12 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-32689 in the wild and no public exploit code.

Affected product: nextcloud security-advisories. 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-2021-32689/ (Markdown: https://insights.sbomify.com/CVE-2021-32689/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32689
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32689
- OSV: https://osv.dev/vulnerability/CVE-2021-32689

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32689/
Summaries are generated and may contain mistakes; the official description above is the record.