# CVE-2016-9463: Auth bypass in 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

> An unauthenticated attacker can bypass authentication and access accounts if the optional SMB backend is configured with anonymous access enabled.

- **Severity:** High 8.1 (`CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 Mar 2017
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-4r4x-7f2r-2f4c

## What is CVE-2016-9463?

CVE-2016-9463 is a high-severity authentication bypass vulnerability in Nextcloud Nextcloud Server, published on 28 Mar 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-287 (Improper Authentication), CWE-303 (Incorrect Implementation of Authentication Algorithm)

## Which versions are affected by CVE-2016-9463?

It affects 2 products.


Products: Nextcloud Nextcloud Server, Owncloud Owncloud.

## How do I fix CVE-2016-9463?

No fix has been published for CVE-2016-9463 yet. Limit exposure of the affected software until one is available.

## Is CVE-2016-9463 being exploited?

There is no known exploitation of CVE-2016-9463 in the wild and no public exploit code.

## Other vulnerabilities in Nextcloud Nextcloud Server

- [CVE-2021-32802](https://insights.sbomify.com/CVE-2021-32802/): Preview generation used third-party library not suited for user-generated content in Nextcloud server (critical 9.3)
- [CVE-2023-26482](https://insights.sbomify.com/CVE-2023-26482/): Scope of workflow operations is not validated in nextcloud server (critical 9.1)
- [CVE-2018-3775](https://insights.sbomify.com/CVE-2018-3775/): Auth bypass in Nextcloud Server (high 8.8)
- [CVE-2023-35172](https://insights.sbomify.com/CVE-2023-35172/): Nextcloud Server password reset endpoint is not brute force protected (high 8.7)
- [CVE-2023-32320](https://insights.sbomify.com/CVE-2023-32320/): Nextcloud Server's brute force protection allows someone to send more requests than intended (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-9463 and fix it if it is affected.

What it is: CVE-2016-9463 is a high-severity authentication bypass vulnerability in Nextcloud Nextcloud Server, published on 28 Mar 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2016-9463 in the wild and no public exploit code.

Affected product: Nextcloud Nextcloud Server. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2016-9463/ (Markdown: https://insights.sbomify.com/CVE-2016-9463/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-9463
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-9463
- OSV: https://osv.dev/vulnerability/CVE-2016-9463

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From sbomify Insights: https://insights.sbomify.com/CVE-2016-9463/
Summaries are generated and may contain mistakes; the official description above is the record.