title: Bruteforce protection can be bypassed with misconfigured proxy
description: Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. In Nextcloud Server prior to versions 26.0.9 and 27.1.4; as well as Nextcloud Enterprise Server prior to versions 23.0.12.13, 24.0.12.9, 25.0.13.4, 26.0.9, and 27.1.4; when a (reverse) proxy is configured as trusted proxy the server could be tricked into reading a wrong remote address for an attacker, allowing them executing authentication attempts than intended. Nextcloud Server versions 26.0.9 and 27.1.4 and Nextcloud Enterprise Server versions 23.0.12.13, 24.0.12.9, 25.0.13.4, 26.0.9, and 27.1.4 contain a patch for this issue. No known workarounds are available.
problem types: CWE-307: Improper Restriction of Excessive Authentication Attempts
affected:
{
vendor: nextcloud
product: security-advisories
versions:
version: >= 23.0.0, < 23.0.12.13, status: affected
version: >= 24.0.0, < 24.0.12.9, status: affected
version: >= 25.0.0, < 25.0.13.4, status: affected
version: >= 26.0.0, < 26.0.9, status: affected
version: >= 27.0.0, < 27.1.4, status: affected
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: LOW
baseScore: 5.3
baseSeverity: MEDIUM
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
version: 3.1
]