CVE-2026-23277
Description
A flaw was found in the Linux kernel. A null pointer dereference vulnerability exists in the Traffic Equalizer (TEQL) module's interaction with the IP tunneling framework. When a Generic Routing Encapsulation (GRE) tap tunnel acts as a TEQL slave, the system attempts to access uninitialized statistics data, leading to a system crash. This can result in a Denial of Service (DoS).
Statement
A NULL pointer dereference can occur in the tunnel transmit stats path when a gretap device is configured as a TEQL slave. Teql_master_xmit forwards packets to the slave via netdev_start_xmit but fails to update skb dev to the slave device. As a result iptunnel_xmit reads skb dev as the teql0 master and later calls iptunnel_xmit_stats which uses dev tstats. The teql0 master does not allocate tstats so dev tstats is NULL and get_cpu_ptr on the NULL pointer triggers a page fault and crashes the kernel. The issue is not directly network reachable from outside. It requires a specific local network configuration and can be triggered by sending traffic once the devices are set up. Impact is denial of service via kernel crash.
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: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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