CVE-2023-4921: Use-after-free in Linux kernel's net/sched: sch_qfq component
A flaw in the Linux Kernel found. A use-after-free vulnerability in the Linux kernel's net/sched: schqfq component can be exploited to achieve local privilege escalation. When the plug qdisc is used as a class of the qfq qdisc, sending network packets triggers use-after-free in qfqdequeue() due to the incorrect .peek handler of schplug and lack of error checking in aggdequeue().
References: https://github.com/torvalds/linux/commit/8fc134fee27f2263988ae38920bc03da416b03d8
Other sources
A use-after-free vulnerability in the Linux kernel's net/sched: schqfq component can be exploited to achieve local privilege escalation.
When the plug qdisc is used as a class of the qfq qdisc, sending network packets triggers use-after-free in qfqdequeue() due to the incorrect .peek handler of schplug and lack of error checking in aggdequeue().
We recommend upgrading past commit 8fc134fee27f2263988ae38920bc03da416b03d8.
— MITRE
Linux Kernel could allow a local authenticated attacker to gain elevated privileges on the system, caused by a use-after-free flaw in the net/sched: schqfq component. By sending a specially crafted request, an authenticated attacker could exploit this vulnerability to gain elevated privileges.
— IBM
Affected Software
Remediation
Event History
Frequently Asked Questions
What is CVE-2023-4921?
CVE-2023-4921 is a use-after-free vulnerability in the Linux kernel's net/sched: sch_qfq component that can be exploited to achieve local privilege escalation.
How severe is CVE-2023-4921?
CVE-2023-4921 has a severity rating of 7.8 (high).
Which software is affected by CVE-2023-4921?
CVE-2023-4921 affects the Linux Kernel versions 3.8 to 6.6.
How can CVE-2023-4921 be exploited?
CVE-2023-4921 can be exploited by sending network packets when the plug qdisc is used as a class of the qfq qdisc, triggering a use-after-free vulnerability in qfq_dequeue().
Are there any references for CVE-2023-4921?
Yes, you can find references for CVE-2023-4921 at the following links: [Link 1](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8fc134fee27f2263988ae38920bc03da416b03d8) and [Link 2](https://kernel.dance/8fc134fee27f2263988ae38920bc03da416b03d8).