CVE-2023-32320: Nextcloud Server's brute force protection allows someone to send more requests than intended

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-06-22 · updated 2026-06-17
Weakness: CWE-307

Description

Nextcloud Server is a data storage system for Nextcloud, a self-hosted productivity platform. When multiple requests are sent in parallel, all of them were executed even if the amount of faulty requests succeeded the limit by the time the response was sent to the client. This allowed someone to send as many requests the server could handle in parallel to bruteforce protected details instead of the configured limit, default 8. Nextcloud Server versions 25.0.7 and 26.0.2 and Nextcloud Enterprise Server versions 21.0.9.12, 22.2.10.12, 23.0.12.7, 24.0.12.2, 25.0.7 and 26.0.2 contain patches for this issue.

Affected products

Nextcloud Server: from 21.0.0 before 21.0.9.12; from 22.0.0 before 22.2.10.12; from 23.0.0 before 23.0.12.7; from 24.0.0 before 24.0.12.2; from 25.0.0 before 25.0.7; from 26.0.0 before 26.0.2 — fixed in 21.0.9.12, 22.2.10.12, 23.0.12.7, 24.0.12.2, 25.0.7, 26.0.2

How to fix

Upgrade to a fixed version: Nextcloud Server 21.0.9.12, 22.2.10.12, 23.0.12.7, 24.0.12.2. Check the vendor advisory for mitigations.

References

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