title: Nextcloud: Lack of authenticity of metadata keys allows a malicious server to gain access to E2EE folders
description: Nextcloud is an open-source productivity platform. In Nextcloud Desktop client 3.0.0 until 3.8.0, Nextcloud Android app 3.13.0 until 3.25.0, and Nextcloud iOS app 3.0.5 until 4.8.0, a malicious server administrator can gain full access to an end-to-end encrypted folder. They can decrypt files, recover the folder structure and add new files.​ This issue is fixed in Nextcloud Desktop 3.8.0, Nextcloud Android 3.25.0, and Nextcloud iOS 4.8.0. No known workarounds are available.
problem types: CWE-325: Missing Cryptographic Step
affected:
{
vendor: nextcloud
product: security-advisories
versions:
version: >= 3.0.0, < 3.8.0, status: affected
version: >= 3.13.0, < 3.25.0, status: affected
version: >= 3.0.5, < 4.8.0, status: affected
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: PHYSICAL
availabilityImpact: LOW
baseScore: 6.9
baseSeverity: MEDIUM
confidentialityImpact: HIGH
integrityImpact: HIGH
privilegesRequired: HIGH
scope: CHANGED
userInteraction: REQUIRED
vectorString: CVSS:3.1/AV:P/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:L
version: 3.1
]