Nextcloud Desktop: Initialization vector reuse in E2EE allows malicious server admin to break, manipulate, access files
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.7epss 1.1%
exploitation probability
1.1%top 37% of all CVEs
observed exploitation
nono source reports it
The Nextcloud Desktop Client is a tool to synchronize files from Nextcloud Server. Starting with version 3.0.0 and prior to version 3.6.5, a malicious server administrator can recover and modify the contents of end-to-end encrypted files. Users should upgrade the Nextcloud Desktop client to 3.6.5 to receive a patch. No known workarounds are available.
CVSS:3.1/AV:P/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N
Affected products
nextcloud · security-advisoriesReferences
https://ethz.ch/content/dam/ethz/special-interest/infk/inst-infsec/appliedcrypto/education/theses/report_DanieleCoppola.pdfhttps://github.com/nextcloud/desktop/pull/5324https://github.com/nextcloud/security-advisories/security/advisories/GHSA-4p33-rw27-j5fchttps://lists.debian.org/debian-lts-announce/2025/09/msg00018.html