CVE-2025-39724

Kernel panic via unlocked UART startup write

Published Sep 5, 2025 · Updated Sep 5, 2025

Denial of service in the Linux kernel 8250 serial driver allows local users to trigger a kernel panic during UART startup. serial8250_do_startup writes UART_LCR without holding port->lock, allowing concurrent UART access to enter a FIFO-reset path that reads an empty receive buffer. Reachability requires a DesignWare 8250 UART with PSLVERR_RESP_EN enabled and concurrent UART activity; the resulting PSLVERR stops the kernel.

CVSS severity5.5
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Linux kernel 8250 serial driver allows local users to trigger a kernel panic during UART startup. serial8250_do_startup writes UART_LCR without holding port->lock, allowing concurrent UART access to enter a FIFO-reset path that reads an empty receive buffer. Reachability requires a DesignWare 8250 UART with PSLVERR_RESP_EN enabled and concurrent UART activity; the resulting PSLVERR stops the kernel.

The record

CVE
CVE-2025-39724
Published
Sep 5, 2025
Updated
Sep 5, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 5, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 5, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2401577586898b3590db80f8b97a26f81f0f6d4e
  2. Affected versionversion=3.13
  3. Affected versionversion=6d5e79331417886196cb3a733bdb6645ba85bc42
  4. Affected versionversion=c49436b657d0a56a6ad90d14a7c3041add7cf64d <0b882f00655afefbc7729c6b5aec86f7a5473a3d
  5. Affected versionversion=c49436b657d0a56a6ad90d14a7c3041add7cf64d <38c0ea484dedb58cb3a4391229933e16be0d1031
  6. Affected versionversion=c49436b657d0a56a6ad90d14a7c3041add7cf64d <68c4613e89f000e8198f9ace643082c697921c9f
  7. Affected versionversion=c49436b657d0a56a6ad90d14a7c3041add7cf64d <7f8fdd4dbffc05982b96caf586f77a014b2a9353
  8. Affected versionversion=c49436b657d0a56a6ad90d14a7c3041add7cf64d <8e2739478c164147d0774802008528d9e03fb802
  9. Affected versionversion=c49436b657d0a56a6ad90d14a7c3041add7cf64d <b8ca8e3f75ede308b4d49a6ca5081460be01bdb5
  10. Affected versionversion=c49436b657d0a56a6ad90d14a7c3041add7cf64d <c826943abf473a3f7260fbadfad65e44db475460
  11. Affected versionversion=c49436b657d0a56a6ad90d14a7c3041add7cf64d <cb7b3633ed749db8e56f475f43c960652cbd6882

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2401577586898b3590db80f8b97a26f81f0f6d4e; version=3.13; version=6d5e79331417886196cb3a733bdb6645ba85bc42; version=c49436b657d0a56a6ad90d14a7c3041add7cf64d <0b882f00655afefbc7729c6b5aec86f7a5473a3d; version=c49436b657d0a56a6ad90d14a7c3041add7cf64d <38c0ea484dedb58cb3a4391229933e16be0d1031; version=c49436b657d0a56a6ad90d14a7c3041add7cf64d <68c4613e89f000e8198f9ace643082c697921c9f; version=c49436b657d0a56a6ad90d14a7c3041add7cf64d <7f8fdd4dbffc05982b96caf586f77a014b2a9353; version=c49436b657d0a56a6ad90d14a7c3041add7cf64d <8e2739478c164147d0774802008528d9e03fb802; version=c49436b657d0a56a6ad90d14a7c3041add7cf64d <b8ca8e3f75ede308b4d49a6ca5081460be01bdb5; version=c49436b657d0a56a6ad90d14a7c3041add7cf64d <c826943abf473a3f7260fbadfad65e44db475460; version=c49436b657d0a56a6ad90d14a7c3041add7cf64d <cb7b3633ed749db8e56f475f43c960652cbd6882

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.4OracleCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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