CVE-2023-4623

Use-after-free in Linux kernel's net/sched: sch_hfsc (HFSC qdisc traffic control) component

HIGH
7.8
CVSS Score
Published: September 6, 2023 at 01:56 PM UTC
Updated: October 14, 2026 at 10:17 PM UTC
2 products affected across 2 vendorsLinux KernelDebian Linux

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Severity
HIGH7.8
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

2.6.12 ≤ v < 4.14.3274.15 ≤ v < 4.19.2954.20 ≤ v < 5.4.2575.11 ≤ v < 5.15.1325.16 ≤ v < 6.1.535.5 ≤ v < 5.10.1956.2 ≤ v < 6.4.166.5 ≤ v < 6.5.32.6.12
Affected range stops below 4.14.327, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.19.295, so it looks safe — our inference, not a vendor statement
Affected range stops below 5.10.195, so it looks safe — our inference, not a vendor statement
Affected range stops below 5.15.132, so it looks safe — our inference, not a vendor statement
Affected range stops below 5.4.257, so it looks safe — our inference, not a vendor statement
Affected range stops below 6.1.53, so it looks safe — our inference, not a vendor statement
Affected range stops below 6.4.16, so it looks safe — our inference, not a vendor statement
Affected range stops below 6.5.3, so it looks safe — our inference, not a vendor statement
Affected range stops below 6.6, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.8HIGHGoogle
Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-416

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