CVE-2026-89765
Received Received - Intake

Zero-init struct in Linux Kernel timers/itimer

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: timers/itimer: Zero-init old itimerval before copy to userspace On native sparc64, struct __kernel_old_timeval contains a four-byte hole after tv_usec because tv_sec is 64-bit while __kernel_suseconds_t is 32-bit. put_itimerval() fills only the named fields in a stack-allocated __kernel_old_itimerval and copies the entire object to userspace, so getitimer() can expose the two padding holes. Zero-initialize the aggregate before assigning the fields so implicit padding is deterministic before it crosses the user/kernel boundary.

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Meta Information

Published
2026-09-11
Last Modified
2026-09-11
Generated
2026-09-12
AI Q&A
2026-09-11
EPSS Evaluated
N/A
NVD
CVE-2026-89765
EUVD
EUVD-2026-76677

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a memory exposure issue on native sparc64 systems. The problem occurs because a data structure called __kernel_old_timeval has a four-byte gap in memory after the tv_usec field due to size differences between 64-bit tv_sec and 32-bit __kernel_suseconds_t. When the kernel copies this structure to userspace, uninitialized memory in the padding can be exposed to users, potentially leaking sensitive data.

Detection Guidance

This vulnerability is specific to the Linux kernel on native sparc64 systems and involves memory padding in the itimer subsystem. Detection requires checking the kernel version and architecture. Use uname -a to verify if your system is sparc64. If affected, inspect the kernel source or installed package version for the fix.

Impact Analysis

If you are running a Linux system on sparc64 architecture, this vulnerability could allow local users to read uninitialized kernel memory. This might expose sensitive information such as passwords, encryption keys, or other confidential data stored in memory. The impact is limited to systems using sparc64 and does not affect other architectures.

Compliance Impact

This vulnerability could potentially impact compliance with data protection regulations like GDPR or HIPAA if it leads to unauthorized access to personal or sensitive data. Exposure of memory contents might constitute a data breach, requiring notification under these regulations depending on the data involved and applicable laws.

Mitigation Strategies

Apply the latest kernel update from your Linux distribution to patch the vulnerability. If no update is available, consider disabling the affected itimer functionality or migrating to a non-sparc64 architecture until patched.

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