CVE-2026-98536

Host hangs via missing Tasks-RCU quiescent states

Published Oct 18, 2026 · Updated Oct 18, 2026

A writeback stall in Linux allows attackers to hang BPF or ftrace detach operations via prolonged cgroup writeback cleanup. In mm/backing-dev.c, cleanup_offline_cgwbs_workfn() relies on cond_resched(), which does not report Tasks-RCU quiescent states under affected preemption modes. The condition requires prolonged cgroup writeback draining overlapping a Tasks-RCU grace-period wait; blocked detach operations stall dependent tasks, and a hung-task detector configured to panic crashes the host.

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

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Get started

Summary

What happened

A writeback stall in Linux allows attackers to hang BPF or ftrace detach operations via prolonged cgroup writeback cleanup. In mm/backing-dev.c, cleanup_offline_cgwbs_workfn() relies on cond_resched(), which does not report Tasks-RCU quiescent states under affected preemption modes. The condition requires prolonged cgroup writeback draining overlapping a Tasks-RCU grace-period wait; blocked detach operations stall dependent tasks, and a hung-task detector configured to panic crashes the host.

The record

CVE
CVE-2026-98536
Published
Oct 18, 2026
Updated
Oct 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
Unavailable
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

Compare your product and version with the public record. A matching version still requires validation against your environment.

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 <260f586a80e7f624dd7f069898a75a904f34d373
  3. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <407a5d205179a4ab186571b0e16ec42725dc77bc
  4. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <42462b5bb0dec57db7f85d0f77655c737d45754d
  5. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <4eb889649eaf65f4a5727b04ba1c017b7d05bb16
  6. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <863049b4018237d1590cd13b16e9fe9c0faad2c6
  7. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <ebf1555ad2821be06f87a88ffd9a2cab8d2200e1
  8. Affected versionversion=c22d70a162d3cc177282c4487be4d54876ca55c8 <fd3bf32279df98751364b3609eb100a3e42f253b

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=5.14; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <260f586a80e7f624dd7f069898a75a904f34d373; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <407a5d205179a4ab186571b0e16ec42725dc77bc; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <42462b5bb0dec57db7f85d0f77655c737d45754d; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <4eb889649eaf65f4a5727b04ba1c017b7d05bb16; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <863049b4018237d1590cd13b16e9fe9c0faad2c6; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <ebf1555ad2821be06f87a88ffd9a2cab8d2200e1; version=c22d70a162d3cc177282c4487be4d54876ca55c8 <fd3bf32279df98751364b3609eb100a3e42f253b

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)
VectorUnavailable
PrivilegesUnavailable
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

See the directory against your own environment.

Your stack

Check the software in your environment

Get started to see how Hinoki identifies affected software and validates exploitability in your environment.

Get started