CVE-2026-68398
Description
A flaw was found in the Linux kernel's Point-to-Point Protocol (PPP) over L2TP (Layer 2 Tunneling Protocol) implementation. An unprivileged user can exploit a Use-After-Free (UAF) vulnerability, where the system attempts to use memory after it has been freed. This can lead to memory corruption, potentially allowing an attacker to cause system instability or execute arbitrary code.
Statement
This vulnerability is rated as an Important impact for Red Hat Enterprise Linux because an unprivileged local attacker can exploit this race condition during socket release to corrupt kernel memory, potentially resulting in local privilege escalation or a complete system crash. Although Layer 2 Tunneling Protocol (L2TP) over PPP is not commonly active by default, the underlying socket family remains accessible to non-root users on standard configurations. Consequently, unauthenticated remote exploitation is not possible, but local users can compromise system integrity without requiring administrative permissions.
Mitigation
If PPP over L2TP functionality is not required, prevent the 'pppol2tp' kernel module from loading to mitigate this vulnerability. Create a file named `/etc/modprobe.d/disable-pppol2tp.conf` with the following content:
install pppol2tp /bin/true
After creating the file, regenerate the initramfs and reboot the system for the changes to take effect. This action may impact services relying on PPP over L2TP.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.8 | N/A | 7.8 |
| 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 | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
