CVE-2026-45282: Nextcloud: Logged-in user bypasses share password and download restrictions on Text attachments via documentId leads to unauthorized file access

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-01 · updated 2026-07-22
Weakness: CWE-284

Description

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, an authenticated attacker can access attachments of link shares when knowing the share token, circumventing password protection or download restrictions. It is applicable to any file that is shared directly, as the attacker only needs to know a documentId they own, apart of the mentioned share token. For shared folders the attacker has to know or guess a documentId of a file that is included inside the folder, making it much harder to exploit. The attacker can only extract an attachments, but not the file shared file or folder itself. It is recommended that the Nextcloud Server is upgraded to 33.0.3 or 32.0.9. It is recommended that the Nextcloud Enterprise Server is upgraded to 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, 29.0.16.16, 28.0.14.17 or 27.1.11.5

Affected products

Nextcloud Server: from 32.0.0 before 32.0.9; from 33.0.0 before 33.0.3; from 27.0.0 before 27.1.11.5; from 28.0.0 before 28.0.14.17; from 29.0.0 before 29.0.16.16; from 30.0.0 before 30.0.17.9 — fixed in 27.1.11.5, 28.0.14.17, 29.0.16.16, 30.0.17.9, 31.0.14.5, 32.0.9

How to fix

Upgrade to a fixed version: Nextcloud Server 27.1.11.5, 28.0.14.17, 29.0.16.16, 30.0.17.9. Check the vendor advisory for mitigations.

References

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