CVE-2026-98538

CPU soft lockups via quadratic inode rescanning

Published Oct 18, 2026 · Updated Oct 18, 2026

Writeback cleanup in Linux allows attackers to stall CPUs via repeated inode scans while draining an offline cgroup's writeback state. cleanup_offline_cgwb() repeatedly scans wb->b_attached and wb->b_dirty_time from the same end, retaining prepared or unswitchable inodes and producing quadratic work under wb->list_lock. Exposure requires an offline cgroup writeback instance with a large inode population; reported CPU stalls lasted 21–48 seconds, and the required attacker privileges are unspecified.

CVSS severityUnavailable
Unscored
EPSS probability0.21%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Writeback cleanup in Linux allows attackers to stall CPUs via repeated inode scans while draining an offline cgroup's writeback state. cleanup_offline_cgwb() repeatedly scans wb->b_attached and wb->b_dirty_time from the same end, retaining prepared or unswitchable inodes and producing quadratic work under wb->list_lock. Exposure requires an offline cgroup writeback instance with a large inode population; reported CPU stalls lasted 21–48 seconds, and the required attacker privileges are unspecified.

The record

CVE
CVE-2026-98538
Published
Oct 18, 2026
Updated
Oct 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.001
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 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=5.14
  2. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <2d1da58c79b66646721a644c6eb4dd1f9c5c9327
  3. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <624dd0931162523d70f9db8c120b5ec6429a9b97
  4. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <9dac137bf77e0683778fb34c86e730c6129e8cb6
  5. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <c96b4d1628868e1195da1a896f79e06f350a3187
  6. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <dd4b92067238771b604b59fdda8efed6d70ee823
  7. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <f6988c90671e83db79df1b7b9d6fdb0e5947fd84

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=5.14; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <2d1da58c79b66646721a644c6eb4dd1f9c5c9327; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <624dd0931162523d70f9db8c120b5ec6429a9b97; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <9dac137bf77e0683778fb34c86e730c6129e8cb6; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <c96b4d1628868e1195da1a896f79e06f350a3187; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <dd4b92067238771b604b59fdda8efed6d70ee823; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <f6988c90671e83db79df1b7b9d6fdb0e5947fd84

Published CVSS scores

No CVSS assessment is available in this record.

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.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.001OS Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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