CVE-2026-99282
Description
A flaw was found in the Linux kernel's Traffic Equalizer (sch_teql) network scheduler. This flaw allows an attacker to cause a Denial of Service (DoS) by transmitting network traffic through an affected network interface. During packet transmission, if a subordinate network device or lower queueing discipline drops a packet, the teql driver fails to recognize that the packet buffer was consumed and freed. Consequently, the kernel attempts to access the already freed buffer, resulting in a use-after-free condition and a system crash.
Statement
This vulnerability is rated as Moderate severity for Red Hat because exploiting it requires local privileges to configure traffic control queueing disciplines and network interfaces, restricting the potential impact to a local denial of service. The True Equalizer (TEQL) scheduler is not configured by default in standard enterprise environments, substantially limiting exposure. In typical deployments, an unprivileged or remote attacker cannot trigger this condition without an administrative configuration linking TEQL with packet-dropping slave devices.
Mitigation
To mitigate this issue, prevent the sch_teql kernel module from loading by executing the following command as root:
# echo "install sch_teql /bin/true" >> /etc/modprobe.d/disable-sch_teql.conf
If the module is currently loaded and not in use, remove it:
# modprobe -r sch_teql
Warning: A system reboot may be required if the module is actively in use and cannot be unloaded. Disabling this module prevents the use of the True Equalizer (TEQL) queueing discipline, which may affect network setups that rely on this feature.
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 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
If the expired pointer is used in a read operation, an attacker might be able to control data read in by the application.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the expired pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the expired pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
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