CVE-2023-4623

A use-after-free flaw was found in the Linux kernel's net/sched: sch_hfsc (HFSC qdisc traffic control) component that can be exploited to achieve local privilege escalation. If a class with a link-sharing curve, for example, with the HFSC_FSC flag set, has a parent without a link-sharing curve, then init_vf() will call vttree_insert() on the parent, but vttree_remove() will be skipped in update_vf(). This leaves a dangling pointer that can cause a use-after-free issue.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, prevent the module sch_hfsc from being loaded by blacklisting the module to prevent it from loading automatically.

https://access.redhat.com/solutions/41278