CVSS 3.1
8.8 highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:HCVE-2021-3491
High (8.8). EPSS 0.6% chance of exploitation in the next 30 days.
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).
Severity
- EPSS
- 0.6% chance of exploitation in the next 30 days; higher than 50% of CVEs (scores of 2026-11-01)
- CWEs
- CWE-787, CWE-131
- Published
- Modified
- Record from
- the NVD, synced
Affected
- canonical:ubuntu_linux
- linux:linux_kernel
References
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d1f82808877bb10d3deee7cf3374a4eb3fb582db
- https://security.netapp.com/advisory/ntap-20210716-0004/
- https://ubuntu.com/security/notices/USN-4949-1
- https://ubuntu.com/security/notices/USN-4950-1
- https://www.openwall.com/lists/oss-security/2021/05/11/13