CVE-2026-72073

Received Received - Intake

Use-After-Free in Linux Kernel vub300 Driver

Publication date: 2026-08-15

Last updated on: 2026-08-17

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: mmc: vub300: fix use-after-free on probe failure The vub300 driver lifetime-manages its controller state using vub300->kref, with vub300_delete() freeing the mmc host when the last reference is dropped. The probe error path after the inactivity timer has been armed still bypasses that lifetime rule, however, and falls through to mmc_free_host() directly if mmc_add_host() fails. The race window is between arming the inactivity timer and reaching the probe error unwind after mmc_add_host() fails: probe thread timer/workqueue ------------ --------------- kref_init(&vub300->kref) ref = 1 kref_get(&vub300->kref) ref = 2, timer ref add_timer(inactivity_timer) fires after one second | | race window |<----------------------------------------------------> | mmc_add_host(mmc) inactivity timer fires vub300_queue_dead_work() kref_get() ref = 3 queue_work(deadwork) mmc_add_host() fails timer_delete_sync() mmc_free_host(mmc) frees vub300 deadwork runs use-after-free The inactivity timeout is one second, so this would require mmc_add_host() to both fail and take more than one second to do so. This is unlikely to happen in practice, but the error path is still wrong. timer_delete_sync() only waits for the timer callback itself. It does not flush deadwork that the callback may already have queued. As a result, queued deadwork can still hold a kref while the probe error path directly frees the backing mmc host, including the vub300 storage. Fix this by using the same lifetime mechanism as disconnect. Clear vub300->interface so that the timer callback and any queued deadwork return early and drop their references, then drop the initial probe reference and return without falling through to err_free_host.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-08-15

Last Modified

2026-08-17

Generated

2026-09-04

AI Q&A

2026-08-15

EPSS Evaluated

2026-09-03

NVD

CVE-2026-72073

EUVD

EUVD-2026-59031

Affected Vendors & Products

Vendor	Product	Version / Range
linux_kernel	mmc	vub300

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This is a use-after-free vulnerability in the Linux kernel's vub300 driver. It occurs when the probe function fails after arming an inactivity timer. The timer's callback may still run and try to access freed memory because the error path does not properly synchronize with the timer's workqueue. The fix ensures the timer callback exits early by clearing a flag, preventing the use-after-free.

Detection Guidance

This vulnerability is specific to the Linux kernel's vub300 driver and requires kernel-level detection. Check if your system uses the vub300 driver with commands like 'lsmod | grep vub300'. If loaded, monitor for probe failures or use-after-free errors in kernel logs with 'dmesg | grep vub300' or 'journalctl -k | grep vub300'.

Impact Analysis

This vulnerability could cause system crashes or memory corruption if exploited. However, the race window is very small (one second) and unlikely in practice. Successful exploitation would require a specific failure scenario during driver initialization.

Compliance Impact

This vulnerability is a use-after-free issue in the Linux kernel's mmc vub300 driver, which could lead to memory corruption or crashes. It does not directly affect compliance with standards like GDPR or HIPAA, as those focus on data protection, privacy, and security controls rather than kernel memory management flaws.

Mitigation Strategies

Update your Linux kernel to a patched version where this issue is resolved. If you cannot update immediately, consider unloading the vub300 driver with 'modprobe -r vub300' if not in use, but this may affect MMC/SD card functionality.

Hi! I’m here to help you understand CVE-2026-72073. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70