CVE-2026-63996

A flaw was found in the Linux kernel's ethtool CMIS (Common Management Interface Specification) module. A malicious SFP (Small Form-Factor Pluggable) module could provide a reply with a length longer than expected, leading to an out-of-bounds write. This vulnerability can result in memory corruption within the kernel, potentially compromising system stability or integrity.

This vulnerability is rated as having a Moderate impact for Red Hat products because triggering it requires physical access to attach a malicious or malfunctioning optical transceiver module to the system. While standard server deployments do not automatically execute untrusted firmware management commands against pluggable transceivers, processing anomalous responses during diagnostic or management routines could cause memory corruption. Because exploiting the condition is constrained by hardware-level prerequisites and local interface interaction rather than remote network vectors, the flaw poses a limited operational risk.

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 don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.