CVE-2026-80584

A flaw was found in the Linux kernel's s390/qeth component. This vulnerability allows a local attacker to trigger an integer underflow when handling user-supplied buffer lengths in the qeth_snmp_command() and qeth_l3_arp_query() functions. This can lead to an out-of-bounds write, potentially causing memory corruption and system instability or a denial of service.

A kernel heap out of bounds write is possible in the s390 qeth SNMP and ARP query ioctl paths because qeth_snmp_command() and qeth_l3_arp_query() accept a user supplied udata_len that can be smaller than the fixed reply offset. The later bounds check subtracts udata_offset from udata_len using u32 arithmetic, so a too small length can underflow and make the check pass before memcpy writes past the allocated buffer. For the CVSS the PR:L is used because a local user or process can reach the ioctl interface in plausible deployments, while full administrator privileges are not clearly required by the bug class. The issue is not directly network reachable because the trigger is a local ioctl rather than packet traffic. Impact is at least a local denial of service via kernel crash and in the paranoid case may allow confidentiality and integrity impact due to kernel heap memory corruption.

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.