VulnerabilityPublished 28 Oct 2026

CVE-2026-99103: Linux kernel · workqueue: Fix unbound pool lifetime for pending pwqs

Source GCVE Database

Authoritative record:CVE-2026-99103

Not known to be exploited · fixed in f320b85c90fe5fc9d4d06badd450518323a94a7f : patch Linux kernel soon.

Data as of 28 Oct 2026, 14:27 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Patch: Available – fixed in f320b85c90fe5fc9d4d06badd450518323a94a7f, cf9c8aaea0d47410df8708bec195889f3a85cd3c, 6741dd3fd38e47c08bc39d11ef5fa141fa6d0441 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 28 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-qwjv-757x-9f99

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=6.6.23 <6.6.25 >=6.8.2 <6.8.4 >=6.7.11 <6.8	Fixed in f320b85c90fe5fc9d4d06badd450518323a94a7f cf9c8aaea0d47410df8708bec195889f3a85cd3c 6741dd3fd38e47c08bc39d11ef5fa141fa6d0441 9f5d5aef3072a33c6f9bfb954bb0cba1c2541849 6.8.4 6.8 6.6.25 3d2ef2b9f4c084ab498494d26495a82f7e15407b
LinuxLinux	Affected =6.9	Fixed in–

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel source. Users should update to a kernel version that includes this patch to prevent the use-after-free condition. No alternative mitigations are described.

Description

A use-after-free vulnerability in the Linux kernel's workqueue subsystem was fixed by correcting the lifetime management of unbound worker pools for pending per-CPU workqueues (pwqs). The flaw allowed a freed worker_pool to be accessed, causing a kernel slab-use-after-free error detected by KASAN.

Impact

The vulnerability can cause kernel memory corruption due to use-after-free, potentially leading to kernel crashes or undefined behavior. It affects the stability and security of the Linux kernel by allowing access to freed memory structures within the workqueue subsystem.

Summary

CVE-2026-99103 addresses a use-after-free bug in the Linux kernel workqueue implementation. Specifically, the issue occurs when canceling the last inactive work skips decrementing the active count, leaving an empty per-CPU workqueue (pwq) on the pending_pwqs list with a zero reference count. The pwq_release_workfn function prematurely releases the worker_pool before removing the pwq from pending_pwqs. This can cause the pool to be freed via RCU while the pwq still references it, leading node_activate_pending_pwq() to attempt locking a freed pool->lock, triggering a slab-use-after-free detected by KASAN. The fix removes the pwq from pending_pwqs before releasing the pool, preventing access to freed memory.

References

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