VulnerabilityPublished 18 Oct 2026

CVE-2026-98536: Linux kernel · writeback: report a Tasks-RCU quiescent state per cgwb drain pass

Source GCVE Database

Authoritative record:CVE-2026-98536· High

Not known to be exploited · fixed in fd3bf32279df98751364b3609eb100a3e42f253b : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

Severity

High

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in fd3bf32279df98751364b3609eb100a3e42f253b, ebf1555ad2821be06f87a88ffd9a2cab8d2200e1, 863049b4018237d1590cd13b16e9fe9c0faad2c6 +4

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-hq8j-r79p-42p5

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ c22d70a162d3cc177282c4487be4d54876ca55c8, < fd3bf32279df98751364b3609eb100a3e42f253b	Fixed in fd3bf32279df98751364b3609eb100a3e42f253b
LinuxLinux	Affected ≥ c22d70a162d3cc177282c4487be4d54876ca55c8, < ebf1555ad2821be06f87a88ffd9a2cab8d2200e1	Fixed in ebf1555ad2821be06f87a88ffd9a2cab8d2200e1
LinuxLinux	Affected ≥ c22d70a162d3cc177282c4487be4d54876ca55c8, < 863049b4018237d1590cd13b16e9fe9c0faad2c6	Fixed in 863049b4018237d1590cd13b16e9fe9c0faad2c6
LinuxLinux	Affected ≥ c22d70a162d3cc177282c4487be4d54876ca55c8, < 42462b5bb0dec57db7f85d0f77655c737d45754d	Fixed in 42462b5bb0dec57db7f85d0f77655c737d45754d
LinuxLinux	Affected ≥ c22d70a162d3cc177282c4487be4d54876ca55c8, < 407a5d205179a4ab186571b0e16ec42725dc77bc	Fixed in 407a5d205179a4ab186571b0e16ec42725dc77bc
LinuxLinux	Affected ≥ c22d70a162d3cc177282c4487be4d54876ca55c8, < 260f586a80e7f624dd7f069898a75a904f34d373	Fixed in 260f586a80e7f624dd7f069898a75a904f34d373

AI-suggested

A fix has been implemented in the Linux kernel to address this issue by adding calls to cond_resched_tasks_rcu_qs() in the drain loop. Users should update to the fixed kernel versions once available. Since this is a kernel-level fix, applying the official kernel update from the vendor or distribution is the recommended remediation. Patch status is not explicitly confirmed in the provided data; users should consult their Linux distribution's security advisories for the official fix availability.

Description

A vulnerability in the Linux kernel related to the writeback subsystem's handling of Tasks-RCU quiescent states during cgroup writeback (cgwb) drain passes has been resolved. The issue causes the drain loop to never report a Tasks-RCU quiescent state on certain kernel preemption models, leading to long-running worker tasks that can stall other kernel operations and potentially cause system panics. The fix involves calling cond_resched_tasks_rcu_qs() to avoid stalling synchronize_rcu_tasks() calls.

Impact

The vulnerability can cause prolonged kernel worker tasks during cgroup writeback draining, which blocks synchronize_rcu_tasks() calls. This blocking can lead to numerous tasks stuck in uninterruptible sleep, triggering the kernel's hung task detector and causing system panics. This affects system stability and reliability, particularly on arm64 and x86 architectures running kernels with PREEMPT_DYNAMIC full or lazy preemption modes.

References

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