CVE-2023-4623: exploitation status and patch state

CVE-2023-4623 · CVSS 7.8 HIGH · EPSS <1%

A use-after-free vulnerability in the Linux kernel's net/sched: sch_hfsc (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 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. We recommend upgrading past commit b3d26c5702c7d6c45456326e56d2ccf3f103e60f.

Is CVE-2023-4623 exploited?

• Not in the CISA KEV catalog.
• EPSS puts exploitation in the next 30 days at <1%.
• Public exploit code: none found in monitored sources.

Which products and versions are affected?

No affected package list recorded here yet.

Is there a patch?

No patch identifier recorded here yet.

What PlainSec published about CVE-2023-4623

• Node Kernel Bugs on GKE COS Nodes Enable Host Escalation (2026-04-15)
• Google Cloud Issues Multiple Linux Kernel Privilege Escalation Fixes for GKE Nodes (2026-04-07)
• Multiple Linux Kernel Flaws Elevate Privileges on GCP Container Nodes (2026-04-03)
• Multiple High-Severity Cloud Vulnerabilities Impact Container Nodes (2026-04-01)

Primary sources

• NVD record

What this record does not say

• No affected package data.
• No patch identifier.

KEV and EPSS are re-checked daily. Record last updated 2026-08-15.