Cloudanix VulnDB

CVE-2026-98749

None

CVSS

—

EPSS

0.2%

Published

Oct 18, 2026

CISA due date

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Cloudanix analysis

Schedule a fix SSVC: Track

A timing bug in a common Linux serial driver can let the system try to use memory that has already been released, which may crash the machine or allow an attacker with local access to take control.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Moderate
Impact
Denial Of Service
Component
OS kernel
Class
Use After Free
Remediation
Patch
Effort
Low
Patch risk
Low

What it actually does

Use-after-free in max3100 serial driver where a polling timer callback can access and re-arm on a port structure that has already been freed during device removal after a suspend bypasses shutdown.

Why it matters to the business

Kernel memory corruption or crash on systems using the max3100 SPI UART, potentially leading to denial of service or local privilege escalation; low public exploitability but requires prompt patching on affected embedded and industrial Linux deployments.

How an attack unfolds

An attacker with local access or ability to control device lifecycle triggers a suspend followed by SPI device unbind before resume completes, leaving the armed timer to fire after the port is freed in max3100_remove and execute arbitrary code via the dangling callback.

How to fix it

Update to a Linux kernel containing the fix that adds timer_shutdown_sync and proper IRQ/workqueue teardown in max3100_remove; apply the patch that keeps timer_delete_sync only in shutdown while ensuring remove always cleans up resources.

How to confirm the fix worked

Confirm kernel source contains the timer_shutdown_sync call and IRQ/workqueue destruction in max3100_remove; test by performing suspend/unbind sequences and verifying no timer remains armed after port free.

Typical attack path

  1. Obtain local access or control over device power management on target system
  2. Force system suspend while max3100 port is active
  3. Unbind or remove the SPI device before resume completes
  4. Trigger timer callback via timeout to access freed port structure
  5. Leverage use-after-free for memory corruption or code execution

How to detect it

Review kernel logs for max3100-related oops or use-after-free warnings during device removal; inspect dmesg and serial driver traces around suspend/resume cycles for evidence of port free while timer is active.

What your security team should do

  • Prioritize kernel upgrade on any system exposing max3100 SPI UART hardware
  • Audit embedded and industrial devices for presence of this driver within 30 days
  • Monitor for future backports to stable kernel branches
  • Restrict unprivileged local access on affected systems until patched

The record

In the Linux kernel, the following vulnerability has been resolved: tty: serial: max3100: shut down timer before freeing port max3100_shutdown() stops the polling timer but returns early during system suspend. If the SPI device is unbound before resume, the serial core does not call max3100_shutdown() again, so max3100_remove() frees the port while the timer remains armed. max3100_timeout() may then access the freed port and re-arm the timer. Add final timer teardown to max3100_remove() and use timer_shutdown_sync() to prevent a racing callback from re-arming it. Also free the IRQ and destroy the workqueue there before freeing the port. Keep timer_delete_sync() in max3100_shutdown() so that a subsequent open() can re-arm the timer. The workqueue is created before request_irq() and destroyed on both request_irq() failure and normal shutdown. Its presence at remove thus identifies the IRQ left registered when suspend bypasses shutdown. Free the IRQ before destroying the workqueue, in both max3100_shutdown() and max3100_remove(), and cancel the pending work in between. free_irq() waits for a running interrupt handler to finish and no new handler can start afterwards, so a racing handler cannot queue work on a workqueue that is being destroyed; the force_end_work check in max3100_dowork() only narrows that window, as a handler delayed between the check and queue_work() could still run after the teardown has cleared the workqueue pointer. Cancelling the work also keeps destroy_workqueue() from waiting on a queued work item in case remove() ever runs while the freezable workqueue is still frozen, e.g. device removal during the resume window, before workqueues are thawed. This issue was found by an in-house static analysis tool.

Affected packages

Ecosystem Package Introduced Fixed