# CVE-2023-4194: Kernel: tap: tap_open(): correctly initialize socket uid next fix of i_uid to current_fsuid

> A local attacker can bypass network filters and gain unauthorized resource access due to incorrect socket UID initialization in the Linux kernel TUN/TAP driver.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 Aug 2023
- **Updated:** 24 Mar 2026
- **Also known as:** AZL-27890, DEBIAN-CVE-2023-4194, GHSA-9cmp-2g73-ff98, UBUNTU-CVE-2023-4194

## What is CVE-2023-4194?

CVE-2023-4194 is a medium-severity authentication bypass vulnerability in Debian Debian Linux, published on 7 Aug 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A flaw was found in the Linux kernel's TUN/TAP functionality. This issue could allow a local user to bypass network filters and gain unauthorized access to some resources. The original patches fixing CVE-2023-1076 are incorrect or incomplete. The problem is that the following upstream commits - a096ccca6e50 ("tun: tun_chr_open(): correctly initialize socket uid"), - 66b2c338adce ("tap: tap_open(): correctly initialize socket uid"), pass "inode->i_uid" to sock_init_data_uid() as the last parameter and that turns out to not be accurate.

Weakness: CWE-863 (Incorrect Authorization), CWE-843 (Access of Resource Using Incompatible Type)

## Which versions are affected by CVE-2023-4194?

It affects 4 products.


Products: Debian Debian Linux, Fedoraproject Fedora, Linux kernel, Redhat Enterprise Linux.

## How do I fix CVE-2023-4194?

Apply the vendor's patch.

## Is CVE-2023-4194 being exploited?

There is no known exploitation of CVE-2023-4194 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-2023-4194 and fix it if it is affected.

What it is: CVE-2023-4194 is a medium-severity authentication bypass vulnerability in Debian Debian Linux, published on 7 Aug 2023. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-4194 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-2023-4194/ (Markdown: https://insights.sbomify.com/CVE-2023-4194/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-4194
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-4194
- OSV: https://osv.dev/vulnerability/CVE-2023-4194

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-4194/
Summaries are generated and may contain mistakes; the official description above is the record.