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Linux KernelOperating system · Linux

CVE-2025-39724

MEDIUM · 5.5 CVSS v3.1 Published 2025-09-05
Fix available
A fix is available. Upgrade to 3.11 / 5.4.297 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 3.10.48, < 3.11>= 3.12.24, < 5.4.297>= 5.5, < 5.10.241>= 5.11, < 5.15.190>= 5.16, < 6.1.149>= 6.2, < 6.6.103>= 6.7, < 6.12.44>= 6.13, < 6.16.4
Debian LinuxOperating system
Affected:= 11.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 3.11 / 5.4.297 / 5.10.241 or later
Fixed in 3.115.4.2975.10.241
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to Linux kernel 5.15.190+ (for 5.15.x), 5.10.241+ (for 5.10.x), 5.4.297+ (for 5.4.x), or the equivalent stable release for other affected branches

  1. 1. Identify the current kernel version using `uname -r` or `cat /proc/version`
  2. 2. Determine which stable kernel branch you are running (e.g., 5.15.x, 5.10.x, 5.4.x)
  3. 3. For 5.15.x branch: upgrade to kernel version 5.15.190 or later
  4. 4. For 5.10.x branch: upgrade to kernel version 5.10.241 or later
  5. 5. For 5.4.x branch: upgrade to kernel version 5.4.297 or later
  6. 6. For 5.5-5.9 and 5.11-5.14 branches: upgrade to the next available stable release that includes the fix (e.g., 5.15.190)
  7. 7. Reboot the system to apply the new kernel
  8. 8. Verify the fix by checking `uname -r` shows the patched version and confirming serial port functionality works normally
Caveat Standard kernel upgrade risks: ensure driver compatibility, review CONFIG changes if using custom kernel configs, and test in staging environment first

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-39724 in production — separate from our analysis above.

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