CVE-2021-47561

What it is

In the Linux kernel, the following vulnerability has been resolved: i2c: virtio: disable timeout handling If a timeout is hit, it can result is incorrect data on the I2C bus and/or memory corruptions in the guest since the device can still be operating on the buffers it was given while the guest has freed them. Here is, for example, the start of a slub_debug splat which was triggered on the next transfer after one transfer was forced to timeout by setting a breakpoint in the backend (rust-vmm/vhost-device): BUG kmalloc-1k (Not tainted): Poison overwritten First byte 0x1 instead of 0x6b Allocated in virtio_i2c_xfer+0x65/0x35c age=350 cpu=0 pid=29 __kmalloc+0xc2/0x1c9 virtio_i2c_xfer+0x65/0x35c __i2c_transfer+0x429/0x57d i2c_transfer+0x115/0x134 i2cdev_ioctl_rdwr+0x16a/0x1de i2cdev_ioctl+0x247/0x2ed vfs_ioctl+0x21/0x30 sys_ioctl+0xb18/0xb41 Freed in virtio_i2c_xfer+0x32e/0x35c age=244 cpu=0 pid=29 kfree+0x1bd/0x1cc virtio_i2c_xfer+0x32e/0x35c __i2c_transfer+0x429/0x57d i2c_transfer+0x115/0x134 i2cdev_ioctl_rdwr+0x16a/0x1de i2cdev_ioctl+0x247/0x2ed vfs_ioctl+0x21/0x30 sys_ioctl+0xb18/0xb41 There is no simple fix for this (the driver would have to always create bounce buffers and hold on to them until the device eventually returns the buffers), so just disable the timeout support for now.

At a glance

Exploitability

Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, data tampering, service disruption.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2024-05-24 15:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-08-04 10:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.2% in the next 30 days (EPSS).
• Severity: 7.8 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2024-05-24 15:15 UTC

Last modified

2026-08-04 10:17 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-416 · Use after free

Record status

Modified

Affected

• Linux Kernel < 5.15.6
• Linux Kernel 5.16

Attack profile CVSS 3.1 · 7.8

Attack vector

Local

Complexity

Low

Privileges needed

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-47561.md and follow it. Check whether this project is affected by CVE-2021-47561. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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