Use-after-free in Linux kernel - CVE-2026-64530
Published: July 27, 2026
Vulnerability identifier: #VU139401
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-64530
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Affected software:
Linux kernel
Red Hat Enterprise Linux Server - AUS
kernel (Red Hat package)
kernel-rt (Red Hat package)
Linux kernel
Red Hat Enterprise Linux Server - AUS
kernel (Red Hat package)
kernel-rt (Red Hat package)
Detailed vulnerability description
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in tcf_qevent_handle in net/sched/cls_api.c when handling TC_ACT_CONSUMED during qevent processing of fragmented traffic. A local user can send specially crafted fragmented network traffic to trigger use of an skb after ownership has been transferred and cause a denial of service.
Exploitation requires RED qdisc qevents together with ct defragmentation and traffic that produces out-of-order fragments.
How to mitigate CVE-2026-64530
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/2140c2f3f2e7b066e1ae616ede8856cafd8015e9
- https://git.kernel.org/stable/c/447d493034a9cf7bf13a2abac86d0573d907ec2f
- https://git.kernel.org/stable/c/5ed3d6f85991656667059d3fa5a1d683ac58c447
- https://git.kernel.org/stable/c/a8a02897f2b479127db261de05cbf0c28b98d159
- https://git.kernel.org/stable/c/e1270e69dcf2c3512c453484178f2e9dc0db3f05
- https://git.kernel.org/stable/c/e28aedab9488343924d227b5a896faed67ce84d5
- https://git.kernel.org/stable/c/f42e8134a3a1074b834a574d404352f867ba994a