CVE-2026-97481
Received Received - Intake

Kernel ISR Soft Lockup in Linux 8250 Serial Driver

Publication date: 2026-09-24

Last updated on: 2026-09-24

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: serial: 8250: fix possible ISR soft lockup There are rare cases in which the host gets stuck in the ISR because it is flooded with messages during the startup phase. The reason for the soft lockup in the ISR is the missing FIFO error IRQ (FIFOE) handling. Not handling it and reporting IRQ_HANDLED triggers the IRQ immediately again. Fix this by adding a check for the FIFOE status and clearing the FIFO if no data is ready (DR). This behavior was observed on an AM62L device which uses the OMAP 8250 driver. Fix it for all 8250 drivers, since the OMAP driver's special IRQ setup handling may trigger this behavior more frequently, but it is not ensured that other 8250 drivers aren't affected.

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Meta Information

Published
2026-09-24
Last Modified
2026-09-24
Generated
2026-09-24
AI Q&A
2026-09-24
EPSS Evaluated
N/A
NVD
CVE-2026-97481
EUVD
EUVD-2026-86079

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux_kernel 8250_driver *

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a potential soft lockup in the serial 8250 driver's Interrupt Service Routine (ISR). During system startup, excessive messages can flood the host, causing it to get stuck in the ISR. The issue occurs because the driver fails to handle FIFO error interrupts (FIFOE), leading to immediate re-triggering of the IRQ due to reporting IRQ_HANDLED incorrectly. The fix involves adding a check for FIFOE status and clearing the FIFO if no data is ready.

Detection Guidance

This vulnerability is specific to the Linux kernel's 8250 serial driver and may cause soft lockups during system startup due to unhandled FIFO error interrupts. Detection requires checking kernel logs for ISR soft lockup messages or unusual serial driver behavior during boot.

Impact Analysis

This vulnerability can cause system instability during startup, leading to delays or failures in booting. In severe cases, it may result in a soft lockup, where the system becomes unresponsive. Systems using the OMAP 8250 driver or other 8250 drivers are particularly at risk, especially during high-message traffic scenarios like boot-up.

Mitigation Strategies

Apply the kernel patch that adds FIFOE status handling in the 8250 serial driver. Update to a Linux kernel version containing the fix. Monitor system logs for ISR soft lockup warnings after applying the update.

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