CVE-2026-89765

A flaw was found in the Linux kernel's timers/itimer component. On native sparc64 systems, the struct __kernel_old_timeval contains uninitialized padding bytes. When put_itimerval() copies this structure to userspace, these padding bytes can be exposed, leading to information disclosure. This vulnerability allows a local attacker to potentially read sensitive kernel memory.

A low impact information disclosure flaw was found in the Linux kernel's timers/itimer subsystem. On native sparc64 systems, struct __kernel_old_timeval contains a four-byte padding hole after tv_usec because tv_sec is a 64-bit type while __kernel_suseconds_t is 32-bit. When handling the getitimer() system call, put_itimerval() initializes only the named fields of a stack-allocated __kernel_old_itimerval and copies the entire structure, including padding, to userspace, so a local unprivileged attacker could read the uninitialized padding bytes, which may disclose small amounts of kernel stack memory. The exposure is limited to native sparc64 systems because the padding hole is specific to that architecture's structure layout. Red Hat Enterprise Linux 6 and 7 are not affected because the vulnerable code is not present in those streams. Red Hat Enterprise Linux 8 and 9 kernels and the OpenShift Container Platform RHCOS components are affected; because this flaw is rated low impact with a Red Hat CVSS 3.1 base score of 5.5, fixes for the affected products are deferred and no update is currently planned. The residual risk is limited to a local attacker potentially reading uninitialized kernel stack data disclosed through the exposed padding bytes on native sparc64 systems.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.