CVE-2026-31770 hwmon: (occ) Fix division by zero in occ_show_power_1()
A division by zero in the Linux kernel's OCC power sensor driver causes a crash during early boot if no samples are collected.
- 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-2026-31770?
CVE-2026-31770 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 May 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:
hwmon: (occ) Fix division by zero in occ_show_power_1()
In occ_show_power_1() case 1, the accumulator is divided by update_tag without checking for zero. If no samples have been collected yet (e.g. during early boot when the sensor block is included but hasn't been updated), update_tag is zero, causing a kernel divide-by-zero crash.
The 2019 fix in commit 211186cae14d ("hwmon: (occ) Fix division by zero issue") only addressed occ_get_powr_avg() used by occ_show_power_2() and occ_show_power_a0(). This separate code path in occ_show_power_1() was missed.
Fix this by reusing the existing occ_get_powr_avg() helper, which already handles the zero-sample case and uses mul_u64_u32_div() to multiply before dividing for better precision. Move the helper above occ_show_power_1() so it is visible at the call site.
[groeck: Fix alignment problems reported by checkpatch]
Weakness: CWE-369
Which versions are affected by CVE-2026-31770?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31770?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-31770 being exploited?
There is no known exploitation of CVE-2026-31770 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-31770, DEBIAN-CVE-2026-31770, GHSA-9842-v9gc-hxx2, ROOT-OS-DEBIAN-11-CVE-2026-31770, ROOT-OS-UBUNTU-2204-CVE-2026-31770, ROOT-OS-UBUNTU-2404-CVE-2026-31770 and 1 more.