Division by zero in Linux kernel - CVE-2026-80847
Published: September 5, 2026
Vulnerability identifier: #VU147070
CSH Severity: Low
CVSS v4: 6.8 [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]
CVE-ID: CVE-2026-80847
CWE-ID: CWE-369
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a divide-by-zero error in tcp_select_initial_window() when processing route-derived advertised MSS values. A local user can configure a route with a too-small RTAX_ADVMSS value to cause a denial of service.
The default advertised MSS path is also affected when the effective advertised MSS is reduced by the route MTU and min_adv_mss.
Affected software
Linux kernel
How to mitigate CVE-2026-80847
Install security update from vendor's repository.