What’s Vulnerable › Vulnerabilities

CVE-2021-32653: Default settings leak federated cloud ID to lookup server of all users

• Severity: low (CVSS 2.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% 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-201

Description

Nextcloud Server is a Nextcloud package that handles data storage. Nextcloud Server versions prior to 19.0.11, 20.0.10, or 21.0.2 send user IDs to the lookup server even if the user has no fields set to published. The vulnerability is patched in versions 19.0.11, 20.0.10, and 21.0.2; no workarounds outside the updates are known to exist.

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-396j-vqpr-qg45
• https://hackerone.com/reports/1173436
• https://security.gentoo.org/glsa/202208-17
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-396j-vqpr-qg45
• https://hackerone.com/reports/1173436
• https://security.gentoo.org/glsa/202208-17

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