CVE-2026-64530
Description
A flaw was found in the Linux kernel's traffic control (TC) classifier application programming interface (API). The tcf_qevent_handle function does not properly handle a consumed socket buffer (skb) when it is processed by the defragmentation engine. This can lead to a Use-After-Free (UAF) vulnerability, where the system attempts to use memory that has already been freed. An attacker could potentially exploit this to cause system instability or execute arbitrary code.
Statement
This Important flaw in the Linux kernel's networking scheduler can lead to a use-after-free vulnerability. Exploitation requires a local attacker to configure specific tc qdisc and tc filter rules involving RED qdisc with early drop events and connection tracking on fragmented network traffic. This non-default configuration limits the attack surface, but successful exploitation could lead to privilege escalation or a denial of service.
Mitigation
To mitigate this issue, avoid configuring the Linux kernel's traffic control (tc) subsystem with the RED queue discipline (`red`) that includes `qevent early_drop` and an `action ct` filter on interfaces processing fragmented UDP streams. This specific configuration is required to trigger the use-after-free vulnerability.
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 | 7.8 | N/A | 9.8 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| 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:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Other
Technical Impact: Varies by Context
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
