CVE-2026-63987 ethtool: coalesce: cap profile updates at NET_DIM_PARAMS_NUM_PROFILES

High 7.8 Published 19 Jul 2026 Updated 19 Oct 2026

A missing bounds check in the Linux kernel's ethtool coalesce profile update allows a local attacker to trigger a heap buffer overflow, potentially leading to code execution or privilege escalation.

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-2026-63987?

CVE-2026-63987 is a high-severity memory corruption vulnerability in Linux kernel, published on 19 Jul 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:

ethtool: coalesce: cap profile updates at NET_DIM_PARAMS_NUM_PROFILES

ethnl_update_profile() walks the ETHTOOL_A_PROFILE_IRQ_MODERATION nest list with an index 'i' and writes new_profile[i++] without bounding i. The destination is kmemdup()'d at NET_DIM_PARAMS_NUM_PROFILES entries (5), but the Netlink nest count is entirely user-controlled. Netlink policies do not have support for constraining the number of nested entries (or number of multi-attr entries).

Weakness: CWE-787

Which versions are affected by CVE-2026-63987?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-63987?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-63987 being exploited?

There is no known exploitation of CVE-2026-63987 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2026-63987, DEBIAN-CVE-2026-63987, GHSA-88qj-mcxj-4mfv, UBUNTU-CVE-2026-63987.