Race condition in Linux kernel - CVE-2026-98603

Vulnerability identifier: #VU156909

CSH Severity: Low

CVSS v4: 2 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98603

CWE-ID: CWE-362

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to disrupt VPN packet routing, potentially causing a denial of service.

The vulnerability exists due to a race condition in the Linux kernel ovpn UDP output functions when clearing a remembered local source address that is no longer usable during concurrent transmissions. A local user can trigger concurrent use of the affected output path to cause lockless IPv6 readers to observe a partially updated source address, potentially disrupting VPN traffic.

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/72bd1bea37ea2c8553938f086bf48ccd2147dfe1
• https://git.kernel.org/stable/c/7d8104988f423572df1f3347ce578037b1043f34
• https://git.kernel.org/stable/c/c44a04722f7dae9a45a101b8e100931ab59f1c18

• Race condition in Linux kernel net ovpn driver
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more