PT-2023-8431 · Nextcloud+2 · Nextcloud Server+3

Christophwurst · Published 2023-06-23 · Updated 2025-01-24 · CVE-2023-35927

Positive Technologies (AI Summary)

CVSS v2.0

8.5

High

Base vector

AV:N/AC:L/Au:S/C:N/I:C/A:C

Name of the Vulnerable Software and Affected Versions Nextcloud Server versions 25.0.0 through 25.0.7 Nextcloud Server versions 26.0.0 through 26.0.2 Nextcloud Enterprise Server versions 21.0.0 through 21.0.9.12 Nextcloud Enterprise Server versions 22.0.0 through 22.2.10.12 Nextcloud Enterprise Server versions 23.0.0 through 23.0.12.7 Nextcloud Enterprise Server versions 24.0.0 through 24.0.12.2 Nextcloud Enterprise Server versions 25.0.0 through 25.0.7 Nextcloud Enterprise Server versions 26.0.0 through 26.0.2

Description The issue is related to inadequate access control in the index.php component of Nextcloud Server and Nextcloud Enterprise Server, which are part of a self-hosted productivity platform providing file storage for Nextcloud. When two servers are registered as trusted servers for each other and have successfully exchanged share secrets, a malicious server could modify or delete VCards in the system address book on the origin server. This would impact the available and shown information in certain places, such as the user search and avatar menu. If a manipulated user modifies their own data in the personal settings, the entry is fixed again.

Recommendations For Nextcloud Server versions 25.0.0 through 25.0.7, update to version 25.0.7 or later. For Nextcloud Server versions 26.0.0 through 26.0.2, update to version 26.0.2 or later. For Nextcloud Enterprise Server versions 21.0.0 through 21.0.9.12, update to version 21.0.9.12 or later. For Nextcloud Enterprise Server versions 22.0.0 through 22.2.10.12, update to version 22.2.10.12 or later. For Nextcloud Enterprise Server versions 23.0.0 through 23.0.12.7, update to version 23.0.12.7 or later. For Nextcloud Enterprise Server versions 24.0.0 through 24.0.12.2, update to version 24.0.12.2 or later. For Nextcloud Enterprise Server versions 25.0.0 through 25.0.7, update to version 25.0.7 or later. For Nextcloud Enterprise Server versions 26.0.0 through 26.0.2, update to version 26.0.2 or later. As a temporary workaround, remove all trusted servers in the "Administration" > "Sharing" settings /index.php/settings/admin/sharing. Afterwards, trigger a recreation of the local system address book with the following occ dav:sync-system-addressbook.

Exploit

Fix

Improper Access Control

Weakness Enumeration

CWE-284

Related Identifiers

ALT-PU-2023-7785

ALT-PU-2025-1855

BDU:2024-00715

CVE-2023-35927

GHSA-H7F7-535F-7Q87

Affected Products

Alt Linux

Nextcloud Enterprise Server

Nextcloud Server

Red Os

References · 11

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/35xxx/CVE-2023-35927.json · Exploit
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-h7f7-535f-7q87 · Vendor Advisory
• https://bdu.fstec.ru/vul/2024-00715 · Security Note
• https://osv.dev/vulnerability/CVE-2023-35927 · Vendor Advisory
• http://repo.red-soft.ru/redos/7.3c/x86_64/updates · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2023-35927 · Security Note
• https://github.com/nextcloud/server/pull/38247 · Note
• https://t.me/cvenotify/52987 · Telegram Post
• https://redos.red-soft.ru/support/secure/uyazvimosti/support/secure/uyazvimosti/mnozhestvennye-uyazvimosti-nextcloud-cve-2023-35171-cve-2023-35927 · Note
• https://t.me/cvenotify/53003 · Telegram Post
• https://hackerone.com/reports/1976754 · Note