CVE-2026-45159: Nextcloud Security-Advisories

Low severity, CVSS 3.5. EPSS: 0.4% chance of exploitation in the next 30 days.

Nextcloud is an open source content collaboration platform. From versions 1.15.0 to before 1.15.4, 1.16.0 to before 1.16.3, 1.17.0 to before 1.17.1, and 1.18.0 to before 1.18.1, a malicious user with access to an end-to-end encrypted files drop link was able to also drop files into other end-to-end encrypted folders of the share owner. Reading and modifying of other files was not possible. This issue has been patched in versions 1.15.4, 1.16.3, 1.17.1, 1.18.1, and 2.0.0-rc.7.

Affected products

• Nextcloud Security-Advisories: from 1.15.0, before 1.15.4 (fixed in 1.15.4); from 1.16.0, before 1.16.3 (fixed in 1.16.3); from 1.17.0, before 1.17.1 (fixed in 1.17.1); from 1.18.0, before 1.18.1 (fixed in 1.18.1)

Published 2026-06-01. Last modified 2026-07-22.