CVE-2016-9464: 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 Nextc...

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.

Metrics

EPSS Probability

1.62%

73.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions	Update
Nextcloud	Nextcloud Server	< 9.0.54	—
Nextcloud	Nextcloud Server	10.0	Rc1

References

http://www.securityfocus.com/bid/97287Third Party Advisory, VDB Entry
https://github.com/nextcloud/server/commit/3387e5d00fcf6b2ea6b285a091e5743f545e7202Issue Tracking, Patch, Third Party Advisory
https://github.com/nextcloud/server/commit/7289cb5ec0b812992ab0dfb889744b94bc0994f0Issue Tracking, Patch, Third Party Advisory
https://github.com/nextcloud/server/commit/a5471b4a3e3f30e99e4de39c97c0c3b3c2f1618fIssue Tracking, Patch, Third Party Advisory
https://github.com/nextcloud/server/commit/e2c4f4f9aa11bc92e8f2212cce73841b922187e8Issue Tracking, Patch, Third Party Advisory
https://hackerone.com/reports/153905Exploit, Third Party Advisory
https://nextcloud.com/security/advisory/?id=nc-sa-2016-007Patch, Vendor Advisory
http://www.securityfocus.com/bid/97287Third Party Advisory, VDB Entry
https://github.com/nextcloud/server/commit/3387e5d00fcf6b2ea6b285a091e5743f545e7202Issue Tracking, Patch, Third Party Advisory
https://github.com/nextcloud/server/commit/7289cb5ec0b812992ab0dfb889744b94bc0994f0Issue Tracking, Patch, Third Party Advisory
https://github.com/nextcloud/server/commit/a5471b4a3e3f30e99e4de39c97c0c3b3c2f1618fIssue Tracking, Patch, Third Party Advisory
https://github.com/nextcloud/server/commit/e2c4f4f9aa11bc92e8f2212cce73841b922187e8Issue Tracking, Patch, Third Party Advisory
https://hackerone.com/reports/153905Exploit, Third Party Advisory
https://nextcloud.com/security/advisory/?id=nc-sa-2016-007Patch, Vendor Advisory

Timeline

Published: Mar 28, 2017
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2016-9464?

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.

How severe is CVE-2016-9464?

Severity scoring for CVE-2016-9464 is pending analysis. The EPSS model estimates a 1.62% probability of exploitation in the next 30 days.

How do I fix CVE-2016-9464?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

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