What’s Vulnerable › Vulnerabilities

CVE-2021-32654: Attacker can obtain write access to any federated share/public link

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-06-01 · updated 2026-06-17
• Weakness: CWE-639

Description

Nextcloud Server is a Nextcloud package that handles data storage. In versions prior to 19.0.11, 20.0.10, and 21.0.2, an attacker is able to receive write/read privileges on any Federated File Share. Since public links can be added as federated file share, this can also be exploited on any public link. Users can upgrade to patched versions (19.0.11, 20.0.10 or 21.0.2) or, as a workaround, disable federated file sharing.

Affected products

• Nextcloud Server: before 19.0.11; from 20.0.0 before 20.0.10; from 21.0.0 before 21.0.2 — fixed in 19.0.11, 20.0.10, 21.0.2

How to fix

Upgrade to a fixed version: Nextcloud Server 19.0.11, 20.0.10, 21.0.2. Check the vendor advisory for mitigations.

References

• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-jf9h-v24c-22g5
• https://hackerone.com/reports/1170024
• https://security.gentoo.org/glsa/202208-17
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-jf9h-v24c-22g5
• https://hackerone.com/reports/1170024
• https://security.gentoo.org/glsa/202208-17

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