Double free in Linux kernel - CVE-2026-89563
Published: September 12, 2026
Vulnerability identifier: #VU149237
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-2026-89563
CWE-ID: CWE-415
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 double free in ip6_tnl_xmit() when handling errors after expanding packet headroom. A local user can trigger an error after packet headroom expansion to cause a denial of service.
The issue is reachable when collect_md tunnels reject a non-NONE encapsulation type or when ip6_tnl_encap() fails.
Affected software
Linux kernel
How to mitigate CVE-2026-89563
Install security update from vendor's repository.