Incomplete cleanup in Linux kernel - CVE-2026-98595

Vulnerability identifier: #VU156898

CSH Severity: Low

CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98595

CWE-ID: CWE-459

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to degrade UDP packet-processing performance.

The vulnerability exists due to incomplete cleanup of disconnected sockets in the Linux kernel UDP 4-tuple hash table when disconnecting a socket bound to a specific address and port. A local user can create, connect, and disconnect such sockets while keeping them open to retain stale hash entries and force an unnecessary 4-tuple lookup for every packet targeting the corresponding local address and port.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-ibm (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - update to 7.0.0-42.42
linux-aws (Ubuntu package) - update to 7.0.0-1016.17
linux-gcp (Ubuntu package) - update to 7.0.0-1016.18
linux-oracle (Ubuntu package) - update to 7.0.0-1015.16
linux-ibm (Ubuntu package) - update to 7.0.0-1017.17
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-42.42~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1017.17

• https://git.kernel.org/stable/c/9e95b1a94c9c49b4ba722251bbca2759b9c51737
• https://git.kernel.org/stable/c/c21daf37d5ce9a4e234b7c42238ac1e6041e28e4
• https://git.kernel.org/stable/c/d1b5fd969cc53f29d02b82b05a45135de4a6087a

• Incomplete cleanup in Linux kernel ipv4
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more