CVE-2026-74470 scsi: scsi_debug: Fix REPORT ZONES alloc_len underflow OOB write
An integer overflow in the Linux kernel's scsi_debug driver allows an out-of-bounds write, potentially causing a system panic or code execution.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74470?
CVE-2026-74470 is a high-severity vulnerability in Linux, published on 15 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:
scsi: scsi_debug: Fix REPORT ZONES alloc_len underflow OOB write
resp_report_zones() sizes the reply buffer from the CDB allocation length. The v3 fix rounds alloc_len up with ALIGN() before deriving the descriptor count:
rep_max_zones = (ALIGN((u64)alloc_len, RZONES_DESC_HD) - RZONES_DESC_HD) >> ilog2(RZONES_DESC_HD); arr_len = (u64)RZONES_DESC_HD * (rep_max_zones + 1);
For alloc_len in 0xFFFFFFC1..0xFFFFFFFF, ALIGN() rounds up to 0x100000000, so arr_len is 4 GB. On 32-bit, kzalloc()'s size_t is 32-bit and truncates 0x100000000 to 0; kzalloc(0) returns ZERO_SIZE_PTR, which passes the !arr check, and desc = arr + 64 is then dereferenced in the loop -> out-of-bounds write / panic.
Clamp rep_max_zones to devip->nr_zones. The loop already stops at sdebug_capacity (after nr_zones zones), so a report can never hold more than nr_zones descriptors; the clamp does not change the report, it only bounds arr_len to (nr_zones + 1) * RZONES_DESC_HD, a real device property that can never reach 0x100000000.
Which versions are affected by CVE-2026-74470?
How do I fix CVE-2026-74470?
Apply the vendor's patch.
Is CVE-2026-74470 being exploited?
There is no known exploitation of CVE-2026-74470 in the wild and no public exploit code.
Sources
Also known as AZL-96270, BELL-CVE-2026-74470, DEBIAN-CVE-2026-74470, GHSA-jmr9-wc6r-pj32, UBUNTU-CVE-2026-74470.