CVE-2021-37860 Cross-site Scripting in Mattermost

What is CVE-2021-37860?

CVE-2021-37860 is a low-severity cross-site scripting vulnerability in Mattermost Mattermost, published on 22 Sep 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

Official description

Mattermost 5.38 and earlier fails to sufficiently sanitize clipboard contents, which allows a user-assisted attacker to inject arbitrary web script in product deployments that explicitly disable the default CSP.

Weakness: CWE-79

Which versions are affected by CVE-2021-37860?

4 open source packages ship an affected version, including github.com/mattermost/mattermost-server/v5 and github.com/mattermost/mattermost-server. It affects 1 product.

Products include Mattermost Mattermost.

How do I fix CVE-2021-37860?

Upgrade github.com/mattermost/mattermost-server/v5 to 5.39.0 or later.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2021-37860 being exploited?

There is no known exploitation of CVE-2021-37860 in the wild and no public exploit code.

Other vulnerabilities in Mattermost Mattermost

• CVE-2019-20851 Path traversal in n/a Critical 9.1
• CVE-2024-39274 Malicious remote can add users to arbitrary teams and channels High 8.7
• CVE-2024-39777 Malicious remote can invite itself to an arbitrary local channel High 8.7
• CVE-2024-39830 Timing attack during remote cluster token comparison when shared channels are enabled High 8.1
• CVE-2023-3615 Lack of server certificate validation in websockets connection High 8.1

All Mattermost Mattermost vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-hv5f-73mr-7vvj, GO-2022-0604.