CVE intelligence and bounded remediation

CVE-2023-4194 — A flaw was found in the Linux kernel's TUN/TAP functionality

Medium CVSS 5.5

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.

Severity
Medium
CVSS
5.5 (3.1)
Published
2023-08-07
CISA KEV
Not currently listed
Ecosystem
linux/kernel
Weaknesses
CWE-843, CWE-863

Affected products

  • linux / linux_kernel
  • linux / linux_kernel / 6.5
  • redhat / enterprise_linux / 8.0
  • redhat / enterprise_linux / 9.0
  • fedoraproject / fedora / 37
  • fedoraproject / fedora / 38

Showing 6 representative product identities from 12 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authorization bypass, IDOR, and cross-tenant access

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Map object and action authorization checks across API, UI, batch, import/export, and background-job paths.
  • Identify tenant, ownership, role, and policy boundaries for affected resources and administrative operations.
  • Use synthetic fixtures to compare intended access matrices without accessing another user's real data.

Remediate safely

  • Enforce server-side authorization at each resource access and state transition using the authenticated principal and trusted tenant context.
  • Scope data queries by tenant and ownership; treat client-supplied identifiers, roles, and policy claims as untrusted.
  • Add deny-by-default policy tests for horizontal and vertical access across every affected transport.

Authoritative sources

Complete CVE record and remediation plan

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