Description

Nextcloud Server is a space for data storage on Nextcloud, a self-hosted productivity playform. In NextCloud Server versions 25.0.0 until 25.0.7 and 26.0.0 until 26.0.2 and Nextcloud Enterprise Server versions 19.0.0 until 19.0.13.9, 20.0.0 until 20.0.14.14, 21.0.0 until 21.0.9.12, 22.0.0 until 22.2.10.12, 23.0.0 until 23.0.12.7, 24.0.0 until 24.0.12.2, 25.0.0 until 25.0.7, and 26.0.0 until 26.0.2, a user could use this functionality to get access to the login credentials of another user and take over their account. This issue has been patched in Nextcloud Server versions 25.0.7 and 26.0.2 and NextCloud Enterprise Server versions 19.0.13.9, 20.0.14.14, 21.0.9.12, 22.2.10.12, 23.0.12.7, 24.0.12.2, 25.0.7, and 26.0.2.

Three workarounds are available. Disable app files_external. Change config setting "Allow users to mount external storage" to disabled in "Administration" > "External storage" settings `…/index.php/settings/admin/externalstorages`. Change config setting to disallow users to create external storages in "Administration" > "External storage" settings `…/index.php/settings/admin/externalstorages` with the types FTP, Nextcloud, SFTP, and/or WebDAV.

Classification

CVE ID: CVE-2023-35928

CVSS Base Severity: HIGH

CVSS Base Score: 8.5

Affected Products

Vendor: nextcloud

Product: security-advisories

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.24% (probability of being exploited)

EPSS Percentile: 61.59% (scored less or equal to compared to others)

EPSS Date: 2025-02-03 (when was this score calculated)

References

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-637g-xp2c-qh5h
https://github.com/nextcloud/server/pull/38265
https://hackerone.com/reports/1978882

Timeline