Buffer overflow in Linux Kernel
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 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).
EPSS: 0.006 (48.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H.
Affected products
- Linux Kernel — versions trunk, linux-5.12.y, linux-5.11.y
- Linux Linux_kernel
- Canonical Ubuntu_linux — versions 20.04, 20.10, 21.04
Weakness classification (CWE)
References
- security@ubuntu.com (x_refsource_UBUNTU, vendor-advisory, Third Party Advisory)
- security@ubuntu.com (x_refsource_UBUNTU, vendor-advisory, Third Party Advisory)
- security@ubuntu.com (mailing-list, x_refsource_MLIST, Patch, Mailing List, Third Party Advisory)
- security@ubuntu.com (Patch, x_refsource_MISC, Vendor Advisory)
- security@ubuntu.com (VDB Entry, Third Party Advisory, x_refsource_MISC)
- security@ubuntu.com (x_refsource_CONFIRM, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-3491?
- CVE-2021-3491 is a high-severity vulnerability in Linux Kernel, classified under Incorrect Calculation of Buffer Size. CVSS score: 7.8/10. Published 2021-06-04.
- How severe is CVE-2021-3491?
- High severity. CVSS v3 base score is 7.8 out of 10.