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Vulnerabilities/CVE-2023-4623Public Intelligence Dossier
Source: linux · Limited verification•Last verified: •Collection Degraded
CVE-2023-4623Unknown / EvaluatingHIGH (raw)CVSS 7.8CWE-416

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

Published: 06 Sept 2023•Last updated: 15 Oct 2026, 03:47 AM IST•Source identifier: cve-coordination@google.com
Dossier completeness: source-provided sections 2 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
7.8HIGH (raw)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Metric sourcecve-coordination@google.com
EPSS probability
0.3%0.003
Percentile19th
Weakness type
CWE-416
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

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.

SOC priority

High

Actively exploited

Unknown

Publicly disclosed

Unknown

Risk basis: SOC ecosystem technology relevance; HIGH severity; No confirmed exploitation signal in current enrichment

Affected Products & Remediation

2 source-backed products
Affected products and versions (source)
  • linux linux kernel · >= 2.6.12 < 4.14.327; >= 4.15 < 4.19.295; >= 4.20 < 5.4.257; >= 5.5 < 5.10.195; >= 5.11 < 5.15.132; >= 5.16 < 6.1.53; >= 6.2 < 6.4.16; >= 6.5 < 6.5.3 · NVD CPE · Source
  • debian debian linux · 10.0 · NVD CPE · Source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

Not provided by source

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Unknown
Exploited (source statement)
Unknown
Publicly disclosed (source)
Unknown

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

Matched local-privilege-escalation (CVSS AV:L, CVSS PR:L)

Exposure

  1. Identify hosts reporting this CVE, prioritising shared or multi-user systems.Telemetry: DeviceTvmSoftwareVulnerabilities · A local, low-privilege vector matters most where untrusted users can run code. · Rule local-privilege-escalation

Exploitation evidence

  1. Look for low-privileged processes spawning SYSTEM or root-level child processes on affected hosts.Telemetry: DeviceProcessEvents · Hunting hypothesis from the CVSS vector; privilege transitions are a focused starting point, not evidence of attack. · Rule local-privilege-escalation

Response

  1. Confirm the source-stated update on affected hosts.Telemetry: DeviceTvmSoftwareVulnerabilities · Host inventory can verify remediation. · Rule local-privilege-escalation

CISA KEV Record

CISA KEV status was not determined for this record.

Change History & Source Data

— No recorded material change

CNA / source
cve-coordination@google.com
Record status · verification
UPDATED · NVD API
CPE
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*, cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

Evidence & Provenance

3 public sources
git.kernel.orgSource recordnvd.nist.govSource recordkernel.danceSource record

Linked by the query's stored exact CVE association. Review required tables and validation status before use.

Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2023-4623
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2023-4623
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2023-4623"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc
Schema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
Open KQL Library

Correlated briefings

— No published briefing references this CVE

SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.