CVE-2025-21820

MEDIUM EPSS 4.6%
Published Feb 27, 20251y ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
Find Similar
Published Feb 27, 2025 1y ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: tty: xilinx_uartps: split sysrq handling lockdep detects the following circular locking dependency: CPU 0 CPU 1 ========================== ============================ cdns_uart_isr() printk() uart_port_lock(port) console_lock() cdns_uart_console_write() if (!port->sysrq) uart_port_lock(port) uart_handle_break() port->sysrq = ... uart_handle_sysrq_char() printk() console_lock() The fixed commit attempts to avoid this situation by only taking the port lock in cdns_uart_console_write if port->sysrq unset. However, if (as shown above) cdns_uart_console_write runs before port->sysrq is set, then it will try to take the port lock anyway. This may result in a deadlock. Fix this by splitting sysrq handling into two parts. We use the prepare helper under the port lock and defer handling until we release the lock.

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
4.6% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-667

Affected Products 4

VendorProductVersionRange
linuxlinux_kernel*≥4.6  –  <6.1.129
linuxlinux_kernel*≥6.2  –  <6.6.78
linuxlinux_kernel*≥6.7  –  <6.12.14
linuxlinux_kernel*≥6.13  –  <6.13.3

References 7

  • git.kernel.org https://git.kernel.org/stable/c/4410dba9807a17a93f649a9f5870ceaf30a675a3
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/9b88a7c4584ba67267a051069b8abe44fc9595b2
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b06f388994500297bb91be60ffaf6825ecfd2afe
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/de5bd24197bd9ee37ec1e379a3d882bbd15c5065
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e22a97700901ba5e8bf8db68056a0d50f9440cae
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/4410dba9807a17a93f649a9f5870ceaf30a675a3
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/8ea0e7b3d7b8f2f0fc9db491ff22a0abe120801c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/9b88a7c4584ba67267a051069b8abe44fc9595b2
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b06f388994500297bb91be60ffaf6825ecfd2afe
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/de5bd24197bd9ee37ec1e379a3d882bbd15c5065
    Patch