Vulnerability Details : CVE-2021-32688
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.
Vulnerability category: BypassGain privilege
Exploit prediction scoring system (EPSS) score for CVE-2021-32688
Probability of exploitation activity in the next 30 days: 0.24%
Percentile, the proportion of vulnerabilities that are scored at or less: ~ 62 % EPSS Score History EPSS FAQ
CVSS scores for CVE-2021-32688
| Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source |
|---|---|---|---|---|---|
|
7.5
|
HIGH | AV:N/AC:L/Au:N/C:P/I:P/A:P |
10.0
|
6.4
|
NIST |
|
8.8
|
HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
2.8
|
5.9
|
NIST |
|
8.8
|
HIGH | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
2.8
|
5.9
|
GitHub, Inc. |
CWE ids for CVE-2021-32688
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The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.Assigned by: security-advisories@github.com (Primary)
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The product makes files or directories accessible to unauthorized actors, even though they should not be.Assigned by: nvd@nist.gov (Secondary)
References for CVE-2021-32688
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https://github.com/nextcloud/server/pull/27000
Harden apptoken check by rullzer · Pull Request #27000 · nextcloud/server · GitHubPatch;Third Party Advisory
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https://security.gentoo.org/glsa/202208-17
Nextcloud: Multiple Vulnerabilities (GLSA 202208-17) — Gentoo securityThird Party Advisory
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https://hackerone.com/reports/1193321
HackerOnePermissions Required
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https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/BVZS26RDME2DYTKET5AECRIZDFUGR2AZ/
[SECURITY] Fedora 33 Update: nextcloud-19.0.13-1.fc33 - package-announce - Fedora Mailing-ListsMailing List;Third Party Advisory
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https://github.com/nextcloud/security-advisories/security/advisories/GHSA-48m7-7r2r-838r
Application specific tokens can change their own scope · Advisory · nextcloud/security-advisories · GitHubThird Party Advisory
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https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/J63NBVPR2AQCAWRNDOZSGRY5II4WS2CZ/
[SECURITY] Fedora 34 Update: nextcloud-20.0.11-1.fc34 - package-announce - Fedora Mailing-ListsMailing List;Third Party Advisory
Products affected by CVE-2021-32688
- cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
- cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:*
- cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:*
- cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:*:*:*:*