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Vulnerabilities/CVE-2026-99167Public Intelligence Dossier
Source: Microsoft · Limited verification•Last verified: •Collection Degraded
CVE-2026-99167Unknown / EvaluatingImportant (raw)CVSS 7.8

net/sched: fix use-after-free in __tcf_action_put()

Published: 29 Oct 2026•Last updated: 01 Nov 2026, 08:21 PM IST•Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Dossier completeness: source-provided sections 3 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
7.8Important (raw)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U
Metric sourceMicrosoft MSRC CVRF
EPSS probability
0.1%0.001
Percentile3rd
Weakness type
—
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

In the Linux kernel, the following vulnerability has been resolved: net/sched: fix use-after-free in __tcf_action_put() __tcf_action_put() decrements the reference count before decrementing the binding count. Another thread can free the action between these operations, causing the binding-count update to access freed memory. KASAN reports it as: BUG: KASAN: slab-use-after-free in __tcf_action_put+0x327/0x340 Write of size 4 at addr ff11000000d46420 by task tc-put-pause/64 Hold the action IDR mutex across both counter updates and IDR removal, keeping cleanup outside the lock.

SOC priority

High

Actively exploited (source statement)

Unknown

Publicly disclosed

Unknown

Risk basis: SOC ecosystem technology relevance; HIGH severity; Source severity; no confirmed exploitation signal

Affected Products & Remediation

2 source-backed products
Affected products and versions (source)
  • azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 · version range not provided by source · Microsoft MSRC · Source
  • azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 · version range not provided by source · Microsoft MSRC · Source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

  • Microsoft MSRC: Release Notes

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-access-review (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-access-review

Exploitation evidence

  1. Review source-stated impact and relevant application errors on affected hosts; local access alone does not establish privilege escalation.Telemetry: DeviceProcessEvents · The vector establishes local access and low privileges only. Confirm the impact from the advisory before choosing a specific hunt. · Rule local-access-review

Response

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

CISA KEV Record

CISA KEV status was not determined for this record.

Change History & Source Data

— No recorded material change

CNA / source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Record status · verification
UPDATED · Unknown
CPE
Unknown

Evidence & Provenance

3 public sources
api.msrc.microsoft.comSource recordnvd.nist.govSource recordgit.kernel.orgSource 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-2026-99167
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-99167
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-99167"| 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.
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Correlated briefings

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.