CVE & CISA-KEV Catalog

CVE-2021-3491

HIGH
7.8
CVSS v3
NVD

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).

CWE-131CWE-787Out-of-bounds Write

How to fix

Remediation Available
linuxDebian
Fixed in:5.10.38-1CVE-2021-3491
Fixed in:5.10.38-1CVE-2021-3491
Fixed in:5.10.38-1CVE-2021-3491
Fixed in:5.10.38-1CVE-2021-3491
linux-hwe-5.8Ubuntu
Fixed in:5.8.0-53.60~20.04.1USN-4949-1
linux-image-5.10.0-1026-oemUbuntu
Fixed in:5.10.0-1026.27USN-4948-1
linux-image-5.8.0-53-genericUbuntu
Fixed in:5.8.0-53.60~20.04.1USN-4949-1
linux-image-5.8.0-53-generic-64kUbuntu
Fixed in:5.8.0-53.60~20.04.1USN-4949-1
linux-image-5.8.0-53-generic-lpaeUbuntu
Fixed in:5.8.0-53.60~20.04.1USN-4949-1
linux-image-5.8.0-53-lowlatencyUbuntu
Fixed in:5.8.0-53.60~20.04.1USN-4949-1
linux-image-generic-64k-hwe-20.04Ubuntu
Fixed in:5.8.0.53.60~20.04.37USN-4949-1
linux-image-generic-hwe-20.04Ubuntu
Fixed in:5.8.0.53.60~20.04.37USN-4949-1
linux-image-generic-lpae-hwe-20.04Ubuntu
Fixed in:5.8.0.53.60~20.04.37USN-4949-1
linux-image-lowlatency-hwe-20.04Ubuntu
Fixed in:5.8.0.53.60~20.04.37USN-4949-1
linux-image-oem-20.04bUbuntu
Fixed in:5.10.0.1026.27USN-4948-1
linux-image-virtual-hwe-20.04Ubuntu
Fixed in:5.8.0.53.60~20.04.37USN-4949-1
linux-oem-5.10Ubuntu
Fixed in:5.10.0-1026.27USN-4948-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal
Attack ComplexityHigh
Privileges RequiredLow
User InteractionNone
ScopeChanged

Impact

ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

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

Exploit Intelligence

0.63%probability of exploitation in 30 days
46thpercentile

Moderate risk: more likely to be exploited than 46% of all known CVEs.

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.