CVE-2026-23072
Description
A memory leak vulnerability was found in the Linux kernel's L2TP (Layer 2 Tunneling Protocol) implementation. After a code refactoring that moved protocol version validation in l2tp_udp_encap_recv(), the error handling path fails to call l2tp_session_put() to release the session reference. This causes l2tp_session, l2tp_tunnel, and associated socket structures to leak on each failed validation.
Statement
This memory leak was discovered by syzkaller and affects systems using L2TP tunneling. Repeated triggering of the error path through malformed L2TP packets can gradually exhaust kernel memory, leading to denial of service. The leak requires the ability to send L2TP traffic to the affected system.
Mitigation
To mitigate this issue, prevent the l2tp_core module from being loaded if L2TP tunneling is not required. See https://access.redhat.com/solutions/41278 for instructions on how to blacklist a kernel module.
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 | 5.5 | 5.5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
An adversary that can cause a resource counter to become inaccurate may be able to create situations where resources are not accounted for and not released, thus causing resources to become scarce for future needs.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An adversary that can cause a resource counter to become inaccurate may be able to force an error that causes the product to crash or exit out of its current operation.
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