CVE-2021-47239 net: usb: fix possible use-after-free in smsc75xx_bind

What is CVE-2021-47239?

CVE-2021-47239 is a high-severity use after free vulnerability in Linux kernel, published on 21 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

net: usb: fix possible use-after-free in smsc75xx_bind

The commit 46a8b29c6306 ("net: usb: fix memory leak in smsc75xx_bind") fails to clean up the work scheduled in smsc75xx_reset-> smsc75xx_set_multicast, which leads to use-after-free if the work is scheduled to start after the deallocation. In addition, this patch also removes a dangling pointer - dev->data[0].

This patch calls cancel_work_sync to cancel the scheduled work and set the dangling pointer to NULL.

Weakness: CWE-416

Which versions are affected by CVE-2021-47239?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2021-47239?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2021-47239 being exploited?

There is no known exploitation of CVE-2021-47239 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2021-47239, GHSA-747f-wh5x-mp2p, UBUNTU-CVE-2021-47239.