# CVE-2023-35075: HTML injection via channel autocomplete

> Attackers can inject HTML into channel names via autocomplete, potentially altering page appearance, though script execution is prevented.

- **Severity:** Low 3.1 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/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:** Yes
- **Published:** 27 Nov 2023
- **Updated:** 3 Jun 2025
- **Also known as:** GHSA-jcgv-3pfq-j4hr

## What is CVE-2023-35075?

CVE-2023-35075 is a low-severity cross-site scripting vulnerability in Mattermost Mattermost, published on 27 Nov 2023. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Mattermost fails to use  innerText / textContent when setting the channel name in the webapp during autocomplete, allowing an attacker to inject HTML to a victim's page by create a channel name that is valid HTML. No XSS is possible though.

Weakness: CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component)

## Which versions are affected by CVE-2023-35075?

4 open source packages ship an affected version, including github.com/mattermost/mattermost-server/v6 and github.com/mattermost/mattermost/server/v8. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/mattermost/mattermost-server/v6` | Go | All versions | 7.8.13 |
| `github.com/mattermost/mattermost-server/v6` | Go | All versions | 7.8.13 |
| `github.com/mattermost/mattermost/server/v8` | Go | All versions | 8.1.4 |
| `github.com/mattermost/mattermost/server/v8` | Go | All versions | 8.1.4 |

Products: Mattermost Mattermost.

## How do I fix CVE-2023-35075?

Upgrade github.com/mattermost/mattermost-server/v6 to 7.8.13 or later.

## Is CVE-2023-35075 being exploited?

There is no known exploitation of CVE-2023-35075 in the wild and no public exploit code.

## Other vulnerabilities in Mattermost Mattermost

- [CVE-2019-20851](https://insights.sbomify.com/CVE-2019-20851/): Path traversal in n/a (critical 9.1)
- [CVE-2024-39274](https://insights.sbomify.com/CVE-2024-39274/): Malicious remote can add users to arbitrary teams and channels (high 8.7)
- [CVE-2024-39777](https://insights.sbomify.com/CVE-2024-39777/): Malicious remote can invite itself to an arbitrary local channel (high 8.7)
- [CVE-2024-39830](https://insights.sbomify.com/CVE-2024-39830/): Timing attack during remote cluster token comparison when shared channels are enabled (high 8.1)
- [CVE-2023-3615](https://insights.sbomify.com/CVE-2023-3615/): Lack of server certificate validation in websockets connection (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-35075 and fix it if it is affected.

What it is: CVE-2023-35075 is a low-severity cross-site scripting vulnerability in Mattermost Mattermost, published on 27 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-2023-35075 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/mattermost/mattermost-server/v6 (Go): affected all versions; fixed in 7.8.13
- github.com/mattermost/mattermost-server/v6 (Go): affected all versions; fixed in 7.8.13
- github.com/mattermost/mattermost/server/v8 (Go): affected all versions; fixed in 8.1.4
- github.com/mattermost/mattermost/server/v8 (Go): affected all versions; fixed in 8.1.4

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-2023-35075/ (Markdown: https://insights.sbomify.com/CVE-2023-35075/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-35075
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-35075
- OSV: https://osv.dev/vulnerability/CVE-2023-35075

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-35075/
Summaries are generated and may contain mistakes; the official description above is the record.