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Vulnerability DatabaseCVE-2025-21820
CVE-2025-21820:
Linux Kernel vulnerability analysis and mitigation
Overview
CVE-2025-21820 affects the Linux kernel's tty subsystem, specifically the Xilinx UART PS driver. The vulnerability was discovered in February 2025 and involves a potential deadlock condition in the sysrq handling mechanism (Debian Security, Ubuntu Security).
Technical details
The vulnerability stems from a circular locking dependency in the xilinx_uartps driver. The issue occurs when cdns_uart_console_write runs before port->sysrq is set, causing a potential deadlock between uart_port_lock and console_lock. The CVSS v3 Base Score is 5.5 (Medium) (Red Hat CVE).
Impact
When exploited, this vulnerability can result in a system deadlock in systems using the Xilinx UART PS driver, potentially affecting system availability (Kernel Commit).
Mitigation and workarounds
The issue has been fixed by splitting sysrq handling into two parts, using a prepare helper under the port lock and deferring handling until the lock is released. The fix is available in newer kernel versions (Kernel Commit).
Additional resources
Source: This report was generated using AI
Related Linux Kernel vulnerabilities:
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