CVE-2021-32688 Application specific tokens can change their own scope

What is CVE-2021-32688?

CVE-2021-32688 is a high-severity vulnerability in Fedoraproject Fedora, published on 12 Jul 2021. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Nextcloud Server is a Nextcloud package that handles data storage. Nextcloud Server supports application specific tokens for authentication purposes. These tokens are supposed to be granted to a specific applications (e.g. DAV sync clients), and can also be configured by the user to not have any filesystem access. Due to a lacking permission check, the tokens were able to change their own permissions in versions prior to 19.0.13, 20.0.11, and 21.0.3. Thus fileystem limited tokens were able to grant themselves access to the filesystem. The issue is patched in versions 19.0.13, 20.0.11, and 21.0.3. There are no known workarounds aside from upgrading.

Weakness: CWE-552, CWE-285

Which versions are affected by CVE-2021-32688?

It affects 2 products.

Products include Fedoraproject Fedora, Nextcloud Nextcloud Server.

How do I fix CVE-2021-32688?

Upgrade to a fixed version.

Is CVE-2021-32688 being exploited?

There is no known exploitation of CVE-2021-32688 in the wild and no public exploit code.

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All Fedoraproject Fedora vulnerabilities

Sources

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

Also known as GHSA-48m7-7r2r-838r.