CVE-2023-4194

Network-filter bypass via incorrect TUN/TAP socket UID

Published Aug 7, 2023 · Updated Mar 24, 2026

Type confusion in the Linux kernel of Red Hat Enterprise Linux 8 and 9 allows local users to bypass network filters. The tun_chr_open and tap_open paths pass inode->i_uid to sock_init_data_uid instead of current_fsuid, so sockets can receive incorrect root ownership. Exploitation requires local access and CAP_NET_ADMIN; affected filtering or routing rules can then trust attacker-created traffic as root-owned.

CVSS severity5.5
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Type confusion in the Linux kernel of Red Hat Enterprise Linux 8 and 9 allows local users to bypass network filters. The tun_chr_open and tap_open paths pass inode->i_uid to sock_init_data_uid instead of current_fsuid, so sockets can receive incorrect root ownership. Exploitation requires local access and CAP_NET_ADMIN; affected filtering or routing rules can then trust attacker-created traffic as root-owned.

The record

CVE
CVE-2023-4194
Published
Aug 7, 2023
Updated
Mar 24, 2026
Vendor
Red Hat
Product
Red Hat Enterprise Linux 8
Classifications
CWE-863, CWE-843, T1562.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 7, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Red Hat · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
5.5CVE ProgramCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
5.5Red HatCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization
CWE-843Access of Resource Using Incompatible Type ('Type Confusion')
T1562.004Impair Defenses: Disable or Modify System Firewall

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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