CVE-2026-80584 s390/qeth: validate user buffer length in SNMP and ARP query ioctls
A local attacker can exploit an integer underflow in the s390/qeth driver to trigger a buffer overflow, potentially leading to code execution or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-80584?
CVE-2026-80584 is a high-severity vulnerability in Linux, published on 26 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
s390/qeth: validate user buffer length in SNMP and ARP query ioctls
qeth_snmp_command() and qeth_l3_arp_query() allocate a buffer sized by a user-supplied length (udata_len) without checking a lower bound, then set udata_offset to a fixed non-zero value and pass both to a reply callback. The callback bounds-checks the copy with
if ((udata_len - udata_offset) < len)
Both fields are u32, so a udata_len smaller than udata_offset makes the subtraction wrap and the check pass, and the following memcpy() writes past the allocation. A udata_len of 0 also yields ZERO_SIZE_PTR from kzalloc(), which the existing NULL check does not catch.
Reject buffers smaller than udata_offset before allocating, so the callback subtraction can no longer underflow.
Which versions are affected by CVE-2026-80584?
How do I fix CVE-2026-80584?
Apply the vendor's patch.
Is CVE-2026-80584 being exploited?
There is no known exploitation of CVE-2026-80584 in the wild and no public exploit code.
Sources
Also known as AZL-97691, BELL-CVE-2026-80584, DEBIAN-CVE-2026-80584, GHSA-cmjf-x265-ccvj, UBUNTU-CVE-2026-80584.