# CVE-2016-1908: Auth bypass in n/a

> Remote X11 clients can obtain trusted forwarding privileges by exploiting OpenSSH client cookie generation failures and local X11 server configuration issues.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/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:** Yes
- **Published:** 11 Apr 2017
- **Updated:** 29 May 2026
- **Also known as:** DEBIAN-CVE-2016-1908, GHSA-mgwc-m57j-46w8, UBUNTU-CVE-2016-1908

## What is CVE-2016-1908?

CVE-2016-1908 is a critical authentication bypass vulnerability in Debian Debian Linux, published on 11 Apr 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The client in OpenSSH before 7.2 mishandles failed cookie generation for untrusted X11 forwarding and relies on the local X11 server for access-control decisions, which allows remote X11 clients to trigger a fallback and obtain trusted X11 forwarding privileges by leveraging configuration issues on this X11 server, as demonstrated by lack of the SECURITY extension on this X11 server.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2016-1908?

It affects 9 products.


Products: Debian Debian Linux, OpenSSH, Oracle Linux, Redhat Enterprise Linux Desktop, Redhat Enterprise Linux Eus, Redhat Enterprise Linux Server, Redhat Enterprise Linux Server Aus, Redhat Enterprise Linux Server Tus, Redhat Enterprise Linux Workstation.

## How do I fix CVE-2016-1908?

Upgrade to a fixed version.

## Is CVE-2016-1908 being exploited?

There is no known exploitation of CVE-2016-1908 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-1908 and fix it if it is affected.

What it is: CVE-2016-1908 is a critical authentication bypass vulnerability in Debian Debian Linux, published on 11 Apr 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-2016-1908 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2016-1908/ (Markdown: https://insights.sbomify.com/CVE-2016-1908/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-1908
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-1908
- OSV: https://osv.dev/vulnerability/CVE-2016-1908

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-1908/
Summaries are generated and may contain mistakes; the official description above is the record.