Out-of-bounds read in Linux kernel - CVE-2026-99063

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Main Vulnerability Database Vulnerabilities #VU157433

Out-of-bounds read in Linux kernel - CVE-2026-99063

Published: October 23, 2026


Vulnerability identifier: #VU157433
CSH Severity: Low
CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-99063
CWE-ID: CWE-125
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local privileged user to disclose seven bytes of kernel memory beyond an allocated buffer.

The vulnerability exists due to an out-of-bounds read in the Linux kernel device-mapper ioctl implementation when get_result_buffer() sets data_start beyond the end of a minimum-sized buffer. A local privileged user can issue a DM_LIST_DEVICES ioctl with data_size set to 305 to cause ctl_ioctl() to copy seven bytes beyond the allocation back to userspace.


Affected software

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-lowlatency (Ubuntu package)
linux-raspi (Ubuntu package)
linux-azure (Ubuntu package)
linux-gcp (Ubuntu package)
linux-aws (Ubuntu package)
linux-ibm (Ubuntu package)
linux-oracle (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-realtime (Ubuntu package)
linux-lowlatency-hwe-6.8 (Ubuntu package)
linux-azure-fde-6.8 (Ubuntu package)
linux-azure-6.8 (Ubuntu package)
linux-oracle-6.8 (Ubuntu package)
linux-aws-6.8 (Ubuntu package)
linux-gkeop (Ubuntu package)
linux-gke (Ubuntu package)
linux-vmware (Ubuntu package)
linux-ibm-6.8 (Ubuntu package)
linux-gcp-6.8 (Ubuntu package)
linux-aws-fips (Ubuntu package)
linux-gcp-fips (Ubuntu package)
linux-azure-fips (Ubuntu package)
linux-raspi-realtime (Ubuntu package)
linux-realtime-6.8 (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-azure-fde-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux-aws-7.0 (Ubuntu package)

How to mitigate CVE-2026-99063

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 6.8.0-149.149, 7.0.0-43.43
linux-lowlatency (Ubuntu package) - update to 6.8.0-149.149.1
linux-raspi (Ubuntu package) - addressed in versions 6.8.0-1068.72, 7.0.0-1023.23
linux-azure (Ubuntu package) - addressed in versions 6.8.0-1073.82, 7.0.0-1020.21
linux-gcp (Ubuntu package) - addressed in versions 6.8.0-1073.81, 7.0.0-1017.19
linux-aws (Ubuntu package) - addressed in versions 6.8.0-1069.74, 7.0.0-1017.18
linux-ibm (Ubuntu package) - addressed in versions 6.8.0-1069.70, 7.0.0-1018.18
linux-oracle (Ubuntu package) - addressed in versions 6.8.0-1067.71, 7.0.0-1016.18
linux-nvidia (Ubuntu package) - update to 6.8.0-1067.70
linux-realtime (Ubuntu package) - addressed in versions 6.8.1-1064.65, 7.0.0-43.43.1
linux-lowlatency-hwe-6.8 (Ubuntu package) - update to 6.8.0-149.149.1~22.04.1
linux-azure-fde-6.8 (Ubuntu package) - update to 6.8.0-1071.78~22.04.1
linux-azure-6.8 (Ubuntu package) - update to 6.8.0-1073.82~22.04.1
linux-oracle-6.8 (Ubuntu package) - update to 6.8.0-1067.71~22.04.1
linux-aws-6.8 (Ubuntu package) - update to 6.8.0-1069.74~22.04.1
linux-gkeop (Ubuntu package) - update to 6.8.0-1053.57
linux-gke (Ubuntu package) - addressed in versions 6.8.0-1068.77, 7.0.0-1010.11
linux-vmware (Ubuntu package) - update to 6.8.0-1010.10
linux-ibm-6.8 (Ubuntu package) - update to 6.8.0-1069.70~22.04.1
linux-gcp-6.8 (Ubuntu package) - update to 6.8.0-1073.81~22.04.1
linux-aws-fips (Ubuntu package) - update to 6.8.0-1069.74+fips1
linux-gcp-fips (Ubuntu package) - update to 6.8.0-1073.81+fips1
linux-azure-fips (Ubuntu package) - update to 6.8.0-1073.82+fips1
linux-raspi-realtime (Ubuntu package) - update to 6.8.0-2056.58
linux-realtime-6.8 (Ubuntu package) - update to 6.8.1-1064.65~22.04.1
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1016.18~24.04.1
linux-azure-fde-7.0 (Ubuntu package) - update to 7.0.0-1019.19~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1017.19~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1018.18
linux-azure-fde (Ubuntu package) - update to 7.0.0-1019.19
linux-aws-7.0 (Ubuntu package) - update to 7.0.0-1017.18~24.04.1

External References

Related Security Bulletins