CVE-2026-89771

A flaw was found in the Linux kernel. A race condition exists in the ring buffer resizing mechanism, where trace_buffer subbuf_size can be read without proper locking while it is being simultaneously resized. This could allow a local attacker to trigger unpredictable behavior or a denial of service (DoS) by causing system instability.

A Moderate-impact flaw was found in the Linux kernel's tracing ring buffer implementation. The trace_buffer subbuf_size value is read without locking in ring_buffer_read_page() and ring_buffer_read_start(), while it can simultaneously be modified by ring_buffer_subbuf_order_set() during a sub-buffer resize. A local attacker with the privileges required to use kernel tracing facilities could race these operations, causing incorrect ring buffer reads and resulting in unpredictable behavior, system instability, or a denial of service. Red Hat Enterprise Linux 10 and Red Hat In-Vehicle OS 2 are affected, as is OpenShift Container Platform 5 through its RHEL CoreOS 9 based kernel; the fix for these affected products is currently deferred, leaving a residual risk of local denial of service on systems where untrusted users can access tracing functionality. Red Hat Enterprise Linux 6, 7, 8, and 9, including the real-time kernels, and OpenShift Container Platform 4 are not affected because the vulnerable code is not present in those kernel versions. Red Hat rates this flaw Moderate because the technical evidence supports an availability impact only, which differs from the Important severity (CVSS 7.8) in the CVE.org record that additionally assumes confidentiality and integrity impacts.

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.