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CVE-2026-12629 Detail

Description

The ARM PL011 UART driver in drivers/serial/uart_pl011.c fails to acknowledge receive error interrupts. On the PL011, the framing, parity, break, and overrun error interrupts (PL011_IMSC_ERROR_MASK) are cleared only by writing the interrupt-clear register UARTICR; reading the data register clears the RX interrupt and the per-byte RSR status but not the error interrupt status in MIS. The interrupt service routine pl011_isr() acknowledged only the CTS modem-status interrupt and never wrote icr for the error bits, so an asserted error interrupt remains pending after the ISR returns. When an application enables error-interrupt reporting via the public uart_irq_err_enable() API, an attacker who controls the serial peer can deterministically assert these error bits by injecting line errors on the RX line — a baud/stop-bit mismatch or mid-character break (framing/break error), a flipped parity bit (parity error), or FIFO flooding (overrun error). Because the error interrupt is never cleared, the interrupt line stays asserted and the CPU re-enters pl011_isr() immediately and indefinitely, producing an interrupt-storm livelock from which the core makes no forward progress. The impact is an availability-only denial of service (permanent hang), reachable from an external or removable UART peer. Exploitation is gated by configuration: the error interrupt is off by default and no in-tree subsystem enables it, so only applications that explicitly call uart_irq_err_enable() on a PL011-based, interrupt-driven port are affected. The fix makes pl011_isr() acknowledge the pending error bits via uart->icr, breaking the loop, and additionally clears the latched RSR status in pl011_err_check().


Metrics

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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
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URL Source(s) Tag(s)
Zephyr Project
Zephyr Project

Weakness Enumeration

CWE-ID CWE Name Source
CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop') Zephyr Project  

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-12629
NVD Published Date:
08/17/2026
NVD Last Modified:
08/17/2026
Source:
Zephyr Project