CVE-2025-21704 Affecting linux-6.1 package, versions <6.1.129-1~deb11u1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.1% (30th percentile)

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  • Snyk IDSNYK-DEBIAN11-LINUX61-9575981
  • published1 Apr 2025
  • disclosed22 Feb 2025

Introduced: 22 Feb 2025

CVE-2025-21704  (opens in a new tab)

How to fix?

Upgrade Debian:11 linux-6.1 to version 6.1.129-1~deb11u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.1 package and not the linux-6.1 package as distributed by Debian. See How to fix? for Debian:11 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

usb: cdc-acm: Check control transfer buffer size before access

If the first fragment is shorter than struct usb_cdc_notification, we can't calculate an expected_size. Log an error and discard the notification instead of reading lengths from memory outside the received data, which can lead to memory corruption when the expected_size decreases between fragments, causing expected_size - acm-&gt;nb_index to wrap.

This issue has been present since the beginning of git history; however, it only leads to memory corruption since commit ea2583529cd1 ("cdc-acm: reassemble fragmented notifications").

A mitigating factor is that acm_ctrl_irq() can only execute after userspace has opened /dev/ttyACM*; but if ModemManager is running, ModemManager will do that automatically depending on the USB device's vendor/product IDs and its other interfaces.

CVSS Base Scores

version 3.1