CVE-2026-72243
Description
A flaw was found in the Linux kernel's Security-Enhanced Linux (SELinux) module. When using TCP Fast Open, SELinux failed to properly check connect-related permissions. This oversight could allow a local attacker to bypass SELinux network access controls, potentially enabling unauthorized network connections that should have been restricted by security policies.
Mitigation
To mitigate this issue, TCP Fast Open (TFO) can be disabled if not required by applications. Disabling TFO prevents the vulnerable code path from being exercised, thereby eliminating the SELinux permission bypass.
To disable TCP Fast Open:
1. Check the current setting:
`sysctl net.ipv4.tcp_fastopen`
2. To disable it temporarily:
`sudo sysctl -w net.ipv4.tcp_fastopen=0`
3. To make the change persistent across reboots, add or modify the following line in `/etc/sysctl.conf`:
`net.ipv4.tcp_fastopen = 0`
4. Apply the persistent changes:
`sudo sysctl -p`
Disabling TCP Fast Open may impact the performance of applications that utilize this feature for faster connection establishment.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.3 | N/A | 8.4 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Changed |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | Low | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
Understanding the Weakness (CWE)
Access Control
Technical Impact: Bypass Protection Mechanism
Frequently Asked Questions
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