CVE-2026-74266

Kernel crash via premature backlog reduction

Published Aug 15, 2026 · Updated Aug 15, 2026

Null-pointer dereference in Linux 6.17 allows local users to crash the kernel through traffic handled by the DualPI2 qdisc. During peek, sch_dualpi2 calls qdisc_tree_reduce_backlog before restoring qlen, causing a parent callback to deactivate a class that still owns a packet. Reachability requires an affected kernel and a configured DualPI2 queue; the demonstrated consequence is an availability-only kernel crash.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Null-pointer dereference in Linux 6.17 allows local users to crash the kernel through traffic handled by the DualPI2 qdisc. During peek, sch_dualpi2 calls qdisc_tree_reduce_backlog before restoring qlen, causing a parent callback to deactivate a class that still owns a packet. Reachability requires an affected kernel and a configured DualPI2 queue; the demonstrated consequence is an availability-only kernel crash.

The record

CVE
CVE-2026-74266
Published
Aug 15, 2026
Updated
Aug 15, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.17
  2. Affected versionversion=8f9516daedd67097a0c6e463fcb7a42b5ee9d477 <15cd0c93bf4f892d66bc7a93667e2357b5673365
  3. Affected versionversion=8f9516daedd67097a0c6e463fcb7a42b5ee9d477 <466f29477cae2bd1982a066d518a9b20c5a37924
  4. Affected versionversion=8f9516daedd67097a0c6e463fcb7a42b5ee9d477 <bd851b10daee7199a658458b8ce250e95a334500

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.17; version=8f9516daedd67097a0c6e463fcb7a42b5ee9d477 <15cd0c93bf4f892d66bc7a93667e2357b5673365; version=8f9516daedd67097a0c6e463fcb7a42b5ee9d477 <466f29477cae2bd1982a066d518a9b20c5a37924; version=8f9516daedd67097a0c6e463fcb7a42b5ee9d477 <bd851b10daee7199a658458b8ce250e95a334500

Published CVSS scores

5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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