CVE-2026-31412 usb: gadget: f_mass_storage: Fix potential integer overflow in check_command_size_in_blocks()
A malicious USB host can trigger an integer overflow in the Linux kernel's mass storage gadget driver, potentially leading to memory corruption and privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-31412?
CVE-2026-31412 is a medium-severity vulnerability in Linux kernel, published on 10 Apr 2026. 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:
usb: gadget: f_mass_storage: Fix potential integer overflow in check_command_size_in_blocks()
The `check_command_size_in_blocks()` function calculates the data size in bytes by left shifting `common->data_size_from_cmnd` by the block size (`common->curlun->blkbits`). However, it does not validate whether this shift operation will cause an integer overflow.
Initially, the block size is set up in `fsg_lun_open()` , and the `common->data_size_from_cmnd` is set up in `do_scsi_command()`. During initialization, there is no integer overflow check for the interaction between two variables.
So if a malicious USB host sends a SCSI READ or WRITE command requesting a large amount of data (`common->data_size_from_cmnd`), the left shift operation can wrap around. This results in a truncated data size, which can bypass boundary checks and potentially lead to memory corruption or out-of-bounds accesses.
Fix this by using the check_shl_overflow() macro to safely perform the shift and catch any overflows.
Weakness: CWE-190
Which versions are affected by CVE-2026-31412?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31412?
Apply the vendor's patch.
Is CVE-2026-31412 being exploited?
There is no known exploitation of CVE-2026-31412 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-31412, DEBIAN-CVE-2026-31412, GHSA-35q9-fp2v-jhcq, ROOT-OS-DEBIAN-11-CVE-2026-31412, ROOT-OS-DEBIAN-12-CVE-2026-31412, ROOT-OS-DEBIAN-13-CVE-2026-31412 and 3 more.