In the Linux kernel, the following vulnerability has been resolved: serial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx The NXP LPC32xx… (CVE-2026-74653)
A vulnerability in the Linux kernel's serial driver for the NXP LPC32xx UART causes an interrupt storm leading to a CPU livelock on single-core ARM926 systems. The issue arises because the driver does not clear a stuck RX character-timeout interrupt when the RX FIFO is empty, resulting in a level-triggered interrupt that re-fires continuously. This can cause a soft-lockup detected by the kernel. The vulnerability has been resolved by adding a hardware-specific interrupt handler that clears the condition without discarding real data.
AI Analysis
Technical Summary
The Linux kernel's serial: 8250_of driver for the NXP LPC32xx UART (PORT_LPC3220) had a flaw where an RX character-timeout interrupt could be latched while the RX FIFO was empty. The interrupt identification register (IIR) reported UART_IIR_RX_TIMEOUT but the line status register (LSR) data ready bit was clear, causing the interrupt handler to never clear the condition. Because the interrupt is level-triggered, it re-fires immediately, causing an interrupt storm that livelocks the CPU on single-core ARM926 processors. The issue occurs when userspace repeatedly opens the front-panel port (ttyS1), triggering a soft-lockup detected by the kernel. The fix involved adding a hardware-specific interrupt handler for PORT_LPC3220 that performs a throwaway read of the receive holding register (RHR) to clear the timeout condition before continuing normal interrupt handling. This approach aligns with existing workarounds in other 8250 drivers for similar issues.
Potential Impact
On affected systems, specifically single-core ARM926 platforms using the LPC32xx UART, this vulnerability can cause a CPU livelock due to an interrupt storm, resulting in a soft-lockup and potential denial of service. No data corruption or privilege escalation is described. The impact is primarily a system hang or degraded availability.
Mitigation Recommendations
A fix has been implemented in the Linux kernel by adding a hardware-specific interrupt handler for the LPC32xx UART that clears the stuck RX timeout interrupt condition. Users should update to a Linux kernel version that includes this fix. Since this is a kernel-level fix, applying the official kernel update or patch is the recommended remediation. No additional mitigations are indicated.
In the Linux kernel, the following vulnerability has been resolved: serial: 8250_of: clear stuck empty-FIFO RX-timeout on LPC32xx The NXP LPC32xx… (CVE-2026-74653)
Description
A vulnerability in the Linux kernel's serial driver for the NXP LPC32xx UART causes an interrupt storm leading to a CPU livelock on single-core ARM926 systems. The issue arises because the driver does not clear a stuck RX character-timeout interrupt when the RX FIFO is empty, resulting in a level-triggered interrupt that re-fires continuously. This can cause a soft-lockup detected by the kernel. The vulnerability has been resolved by adding a hardware-specific interrupt handler that clears the condition without discarding real data.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel's serial: 8250_of driver for the NXP LPC32xx UART (PORT_LPC3220) had a flaw where an RX character-timeout interrupt could be latched while the RX FIFO was empty. The interrupt identification register (IIR) reported UART_IIR_RX_TIMEOUT but the line status register (LSR) data ready bit was clear, causing the interrupt handler to never clear the condition. Because the interrupt is level-triggered, it re-fires immediately, causing an interrupt storm that livelocks the CPU on single-core ARM926 processors. The issue occurs when userspace repeatedly opens the front-panel port (ttyS1), triggering a soft-lockup detected by the kernel. The fix involved adding a hardware-specific interrupt handler for PORT_LPC3220 that performs a throwaway read of the receive holding register (RHR) to clear the timeout condition before continuing normal interrupt handling. This approach aligns with existing workarounds in other 8250 drivers for similar issues.
Potential Impact
On affected systems, specifically single-core ARM926 platforms using the LPC32xx UART, this vulnerability can cause a CPU livelock due to an interrupt storm, resulting in a soft-lockup and potential denial of service. No data corruption or privilege escalation is described. The impact is primarily a system hang or degraded availability.
Mitigation Recommendations
A fix has been implemented in the Linux kernel by adding a hardware-specific interrupt handler for the LPC32xx UART that clears the stuck RX timeout interrupt condition. Users should update to a Linux kernel version that includes this fix. Since this is a kernel-level fix, applying the official kernel update or patch is the recommended remediation. No additional mitigations are indicated.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-hpjx-f9r3-xj76
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-74653"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a8a27f1acd9273b499bc7ba
Added to database: 08/22/2026, 22:51:29 UTC
Last enriched: 08/23/2026, 00:09:37 UTC
Last updated: 08/23/2026, 01:12:11 UTC
Views: 2
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