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Fencer Vulns
high 8.1

CVE-2016-9463 json

Nextcloud Server before 9.0.54 and 10.0.1 & ownCloud Server before 9.1.2, 9.0.6, and 8.2.9 suffer from SMB User Authentication Bypass.

published 2017-03-28 9 y ago modified 2026-06-17 4 mo ago also EUVD-2016-10269

cvss
8.1
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.1%
EPSS 4.1% chance of exploitation in 30 days, percentile 90%
public exploits
0
none known

Summary

Nextcloud Server before 9.0.54 and 10.0.1 & ownCloud Server before 9.1.2, 9.0.6, and 8.2.9 suffer from SMB User Authentication Bypass. Nextcloud/ownCloud include an optional and not by default enabled SMB authentication component that allows authenticating users against an SMB server. This backend is implemented in a way that tries to connect to a SMB server and if that succeeded consider the user logged-in. The backend did not properly take into account SMB servers that have any kind of anonymous auth configured. This is the default on SMB servers nowadays and allows an unauthenticated attacker to gain access to an account without valid credentials. Note: The SMB backend is disabled by default and requires manual configuration in the Nextcloud/ownCloud config file. If you have not configured the SMB backend then you're not affected by this vulnerability.

Patch / fix

  • nextcloud nextcloud_server 9.0.54, 10.0.1
  • owncloud owncloud 8.2.9, 9.0.4, 9.1.2

Exploit prediction

4.09% chance of exploitation in the next 30 days, higher than 90% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • rhinosecuritylabs.com https://rhinosecuritylabs.com/2016/10/operation-ownedcloud-exploitation-post-exploitation-persistence/ referenced PoC, tagged "exploit" by a source, unverified
  • hackerone.com https://hackerone.com/reports/148151 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 8.1 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • n/a Nextcloud Server & ownCloud Server Nextcloud Server before 9.0.54 and 10.0.1 & ownCloud Server before 9.1.2, 9.0.6, and 8.2.9

Classification

Weakness
  • CWE-303 Incorrect Implementation of Authentication Algorithm
  • CWE-287 Improper Authentication

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.