CVE-2023-4623: Use-after-free in Linux kernel's net/sched: sch_hfsc (HFSC qdisc traffic control) component
A use-after-free vulnerability in the Linux kernel's net/sched: schhfsc (HFSC qdisc traffic control) component can be exploited to achieve local privilege escalation. If a class with a link-sharing curve (i.e. with the HFSCFSC flag set) has a parent without a link-sharing curve, then initvf() will call vttreeinsert() on the parent, but vttreeremove() will be skipped in updatevf(). This leaves a dangling pointer that can cause a use-after-free. We recommend upgrading past commit b3d26c5702c7d6c45456326e56d2ccf3f103e60f.
Other sources
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: schhfsc (HFSC qdisc traffic control) component. By sending a specially crafted request, an authenticated attacker could exploit this vulnerability to gain elevated privileges.
— IBM
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 6.1.176-1Fixed in 6.1.190-1Fixed in 6.12.107-1Fixed in 6.12.113-1Fixed in 7.2.12-1Fixed in 7.2.13-1 - Upgrade
Upgrade
Linux kernel net/sched: sch_hfscto a version that resolves this vulnerability.Patch b3d26c5702c7d6c45456326e56d2ccf3f103e60f
Event History
Frequently Asked Questions
What is CVE-2023-4623?
CVE-2023-4623 is a use-after-free vulnerability in the Linux kernel's net/sched: sch_hfsc (HFSC qdisc traffic control) component that can be exploited to achieve local privilege escalation.
How can CVE-2023-4623 be exploited?
CVE-2023-4623 can be exploited by a local attacker to achieve privilege escalation.
What software is affected by CVE-2023-4623?
The Linux kernel versions up to and including 2.5.75 and version 2.6.12-rc1 are affected by CVE-2023-4623.
What is the severity of CVE-2023-4623?
CVE-2023-4623 has a severity rating of 7.8 (high).
How can I fix CVE-2023-4623?
To fix CVE-2023-4623, it is recommended to update to a patched version of the Linux kernel.