Out-of-bounds write in Linux kernel - CVE-2026-63987
Published: July 20, 2026
Vulnerability identifier: #VU138671
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-63987
CWE-ID: CWE-787
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to an out-of-bounds write in ethnl_update_profile() in the ethtool coalesce handling code when processing a user-controlled Netlink nested attribute list for ETHTOOL_A_PROFILE_IRQ_MODERATION. A local user can send a specially crafted Netlink request with excessive nested profile entries to cause a denial of service.
The number of nested entries is entirely user-controlled, while the destination buffer is allocated for only NET_DIM_PARAMS_NUM_PROFILES entries.
How to mitigate CVE-2026-63987
Install security update from vendor's repository.