Out-of-bounds read in Linux kernel - CVE-2026-64191

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Main Vulnerability Database Vulnerabilities #VU138905

Out-of-bounds read in Linux kernel - CVE-2026-64191

Published: July 21, 2026


Vulnerability identifier: #VU138905
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64191
CWE-ID: CWE-125
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to out-of-bounds read and out-of-bounds write in stub_xfer() in the i2c-stub driver when handling an I2C_SMBUS ioctl with I2C_SMBUS_I2C_BLOCK_DATA and an invalid block length. A local user can issue a crafted ioctl request with data->block[0] greater than 32 to cause a denial of service.

The issue affects the development and test i2c-stub driver, which is not built by default and must be loaded with a chip_addr= parameter.


Affected software

Linux kernel
Red Hat CodeReady Linux Builder for ARM 64
Red Hat CodeReady Linux Builder for Power, little endian
Red Hat CodeReady Linux Builder for x86_64
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for Real Time
Red Hat Enterprise Linux for Real Time for NFV
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux Server - AUS
openEuler
Ubuntu
kernel (Red Hat package)
kernel-rt (Red Hat package)
kernel-debuginfo
python3-perf-debuginfo
kernel-debugsource
kernel-devel
kernel-source
kernel-tools
kernel-tools-debuginfo
kernel-tools-devel
perf
perf-debuginfo
python2-perf
python2-perf-debuginfo
python3-perf
bpftool
kernel
bpftool-debuginfo
kernel-headers
kernel-extra-modules
linux (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)

How to mitigate CVE-2026-64191

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
kernel (Red Hat package) - addressed in versions 4.18.0-305.206.1.el8_4, 4.18.0-372.213.1.el8_6, 4.18.0-553.158.1.el8_10, 5.14.0-687.42.1.el9_8
kernel-rt (Red Hat package) - update to 4.18.0-553.158.1.rt7.499.el8_10
kernel-debuginfo - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
python3-perf-debuginfo - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-debugsource - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-devel - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-source - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-tools - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-tools-debuginfo - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-tools-devel - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
perf - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
perf-debuginfo - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
python2-perf - update to 4.19.90-2608.3.0.0385
python2-perf-debuginfo - update to 4.19.90-2608.3.0.0385
python3-perf - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
bpftool - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
bpftool-debuginfo - addressed in versions 4.19.90-2608.3.0.0385, 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-headers - addressed in versions 5.10.0-327.0.0.228, 6.6.0-145.3.29.160
kernel-extra-modules - update to 6.6.0-145.3.29.160
linux (Ubuntu package) - addressed in versions 7.0.0-31.31, 7.0.0-31.31.1, 7.0.0-31.31~24.04.1, 7.0.0-1006.7, 7.0.0-1011.11~24.04.1, 7.0.0-1012.12, 7.0.0-1012.12~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13

External References

Related Security Bulletins