What’s Vulnerable › Vulnerabilities

CVE-2016-9463

• Severity: high (CVSS 8.1 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 4.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2017-03-28 · updated 2026-06-17
• Weakness: CWE-303

Description

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.

Affected products

• Nextcloud Server: before 9.0.54; from 10.0.0 before 10.0.1 — fixed in 10.0.1, 9.0.54
• Owncloud: from 8.2.0 before 8.2.9; from 9.0.0 before 9.0.4; from 9.1.0 before 9.1.2 — fixed in 8.2.9, 9.0.4, 9.1.2

How to fix

Upgrade to a fixed version: Nextcloud Server 10.0.1, 9.0.54; Owncloud 8.2.9, 9.0.4, 9.1.2. Check the vendor advisory for mitigations.

References

• https://github.com/nextcloud/apps/commit/b85ace6840b8a6704641086bc3b8eb8e81cb2274
• https://github.com/nextcloud/apps/commit/decb91fd31f4ffab191cbf09ce4e5c55c67a4087
• https://github.com/owncloud/apps/commit/16cbccfc946c8711721fa684d78135ca1fb64791
• https://github.com/owncloud/apps/commit/5d47e7b52646cf79edadd78ce10c754290cbb732
• https://github.com/owncloud/apps/commit/a0e07b7ddd5a5fd850a6e07f8457d05b76a300b3
• https://hackerone.com/reports/148151
• https://nextcloud.com/security/advisory/?id=nc-sa-2016-006
• https://owncloud.org/security/advisory/?id=oc-sa-2016-017
• https://rhinosecuritylabs.com/2016/10/operation-ownedcloud-exploitation-post-exploitation-persistence/
• https://github.com/nextcloud/apps/commit/b85ace6840b8a6704641086bc3b8eb8e81cb2274
• https://github.com/nextcloud/apps/commit/decb91fd31f4ffab191cbf09ce4e5c55c67a4087
• https://github.com/owncloud/apps/commit/16cbccfc946c8711721fa684d78135ca1fb64791

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