CVE-2026-23255

Local system hang via incomplete RCU protection

Published Mar 18, 2026 · Updated Mar 18, 2026

An RCU race in /proc/net/ptype in affected Linux Kernel releases allows local users to hang the system during packet-handler changes. ptype_seq_show() reads pt->dev without a barrier while concurrent writers can remove its packet_type and clear the pointer, and ptype_seq_next() reads list links without READ_ONCE(). The trigger requires a local user and concurrent packet-handler removal; the reported consequence is an RCU stall that interrupts the host.

CVSS severity5.5
Medium
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An RCU race in /proc/net/ptype in affected Linux Kernel releases allows local users to hang the system during packet-handler changes. ptype_seq_show() reads pt->dev without a barrier while concurrent writers can remove its packet_type and clear the pointer, and ptype_seq_next() reads list links without READ_ONCE(). The trigger requires a local user and concurrent packet-handler removal; the reported consequence is an RCU stall that interrupts the host.

The record

CVE
CVE-2026-23255
Published
Mar 18, 2026
Updated
Mar 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 18, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <589a530ae44d0c80f523fcfd1a15af8087f27d35
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f613e8b4afea0cd17c7168e8b00e25bc8d33175d
  3. Affected versionversion=2.6.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <589a530ae44d0c80f523fcfd1a15af8087f27d35; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f613e8b4afea0cd17c7168e8b00e25bc8d33175d; version=2.6.12

Published CVSS scores

4.7Oracle LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.7Amazon LinuxCVSS:3.1/AV:L/AC:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application 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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