Cloudanix VulnDB

CVE-2025-21698

None

CVSS

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EPSS

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Published

Feb 12, 2025

CISA due date

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Cloudanix analysis

Schedule a fix SSVC: Track

A software update prevents crashes that could occur on certain computers when using USB connections for serial communication.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Low
Impact
Denial Of Service
Component
OS kernel
Class
Memory Corruption
Remediation
Patch
Effort
Low
Patch risk
Low

What it actually does

Reintroduces a crash condition in the Linux kernel USB gadget u_serial driver by reverting the endpoint disable step before nulling the port, leading to null pointer dereference or related memory corruption on Tegra systems.

Why it matters to the business

Unexpected kernel crashes and system instability on affected Linux distributions using USB gadget serial functionality, particularly embedded or ARM-based devices, potentially causing downtime and requiring immediate patching.

How an attack unfolds

An attacker or automated process exercises USB gadget serial operations on a vulnerable kernel; the missing endpoint disable before port nullification triggers the crash path on Tegra hardware.

How to fix it

Upgrade to fixed kernel packages: linux 6.1.128-1 on Debian 12; upgrade virt-viewer to 9.0-11.el8 on AlmaLinux 8. Reboot after installation and validate USB gadget functionality.

How to confirm the fix worked

Verify installed kernel or package versions match the fixed releases; reproduce USB gadget serial usage on test Tegra hardware and confirm absence of crashes.

Typical attack path

  1. Enumerate or attach to USB gadget serial interface
  2. Trigger port operations that set the port pointer to null
  3. Execute code path without prior endpoint disable
  4. Trigger null dereference and kernel crash

How to detect it

Inspect kernel crash dumps and dmesg logs for entries referencing u_serial, null pointer dereference, or Tegra USB gadget failures around the time of the revert commit.

  • u_serial: port being null
  • Tegra USB gadget crash
  • usb: gadget: u_serial

What your security team should do

  • Apply the listed kernel and package updates within the next maintenance window
  • Prioritize systems with USB gadget or Tegra hardware
  • Monitor kernel logs for u_serial related oops or panics until patched

The record

In the Linux kernel, the following vulnerability has been resolved: Revert "usb: gadget: u_serial: Disable ep before setting port to null to fix the crash caused by port being null" This reverts commit 13014969cbf07f18d62ceea40bd8ca8ec9d36cec. It is reported to cause crashes on Tegra systems, so revert it for now.

Affected packages

Ecosystem Package Introduced Fixed
Debian:11 linux 0 No fix
Debian:12 linux 0 6.1.128-1
Debian:13 linux 0 6.12.12-1

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