What’s Vulnerable › Vulnerabilities

CVE-2016-9464

• Severity: medium (CVSS 4.3 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2017-03-28 · updated 2026-06-17
• Weakness: CWE-285

Description

Nextcloud Server before 9.0.54 and 10.0.0 suffers from an improper authorization check on removing shares. The Sharing Backend as implemented in Nextcloud does differentiate between shares to users and groups. In case of a received group share, users should be able to unshare the file to themselves but not to the whole group. The previous API implementation simply unshared the file to all users in the group.

Affected products

• Nextcloud Server: before 9.0.54; 10.0-rc1 — fixed in 9.0.54

How to fix

Upgrade to a fixed version: Nextcloud Server 9.0.54. Check the vendor advisory for mitigations.

References

• http://www.securityfocus.com/bid/97287
• https://github.com/nextcloud/server/commit/3387e5d00fcf6b2ea6b285a091e5743f545e7202
• https://github.com/nextcloud/server/commit/7289cb5ec0b812992ab0dfb889744b94bc0994f0
• https://github.com/nextcloud/server/commit/a5471b4a3e3f30e99e4de39c97c0c3b3c2f1618f
• https://github.com/nextcloud/server/commit/e2c4f4f9aa11bc92e8f2212cce73841b922187e8
• https://hackerone.com/reports/153905
• https://nextcloud.com/security/advisory/?id=nc-sa-2016-007
• http://www.securityfocus.com/bid/97287
• https://github.com/nextcloud/server/commit/3387e5d00fcf6b2ea6b285a091e5743f545e7202
• https://github.com/nextcloud/server/commit/7289cb5ec0b812992ab0dfb889744b94bc0994f0
• https://github.com/nextcloud/server/commit/a5471b4a3e3f30e99e4de39c97c0c3b3c2f1618f
• https://github.com/nextcloud/server/commit/e2c4f4f9aa11bc92e8f2212cce73841b922187e8

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