#VU105148 Improper locking in Linux kernel - CVE-2025-21820

Vulnerability identifier: #VU105148

Vulnerability risk: Low

CVSSv4.0: 4.3 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2025-21820

CWE-ID: CWE-667

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

Description

The vulnerability allows a local user to perform a denial of service (DoS) attack.

The vulnerability exists due to improper locking within the cdns_uart_handle_rx(), cdns_uart_isr() and cdns_uart_console_write() functions in drivers/tty/serial/xilinx_uartps.c. A local user can perform a denial of service (DoS) attack.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Linux kernel: 6.1 - 6.1.128

---

External links
https://git.kernel.org/stable/c/4410dba9807a17a93f649a9f5870ceaf30a675a3
https://git.kernel.org/stable/c/8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c
https://git.kernel.org/stable/c/9b88a7c4584ba67267a051069b8abe44fc9595b2
https://git.kernel.org/stable/c/b06f388994500297bb91be60ffaf6825ecfd2afe
https://git.kernel.org/stable/c/de5bd24197bd9ee37ec1e379a3d882bbd15c5065
https://mirrors.edge.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.1.129

---

Q & A

Can this vulnerability be exploited remotely?

Is there known malware, which exploits this vulnerability?