CVE-2021-3491: The io_uring subsystem in the Linux kernel allowed the MAX_RW_COUNT limit to be bypassed in the PROVIDE_BUFFERS operation, which led to negative values being usedin mem_rw when…

Description

The io_uring subsystem in the Linux kernel allowed the MAX_RW_COUNT limit to be bypassed in the PROVIDE_BUFFERS operation, which led to negative values being usedin mem_rw when reading /proc/<PID>/mem. This could be used to create a heap overflow leading to arbitrary code execution in the kernel. It was addressed via commit d1f82808877b ("io_uring: truncate lengths larger than MAX_RW_COUNT on provide buffers") (v5.13-rc1) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. It was introduced in ddf0322db79c ("io_uring: add IORING_OP_PROVIDE_BUFFERS") (v5.7-rc1).

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Attack vector

Local

Complexity

Low

Privileges

Low

User interaction

None

Confidentiality

High

Integrity

High

Availability

High

Scope

Changed

Exploitation

Is it being used?

Exploit prediction (EPSS)0.6% · higher than 51% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

KE

Kernel · Linux

5.7 before 5.10.37; 5.11 before 5.11.21; 5.12 before 5.12.4 · source: NVD

UL

Ubuntu Linux · Canonical

20.04; 20.10; 21.04 · source: NVD