Use-after-free in Linux kernel - CVE-2026-63993
Published: July 20, 2026
Vulnerability identifier: #VU138657
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-63993
CWE-ID: CWE-416
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 execute arbitrary code.
The vulnerability exists due to a use-after-free in the vxlan_xmit_one function in drivers/net/vxlan/vxlan_core.c when processing packets after skb_tunnel_check_pmtu() updates the skb head. A local user can trigger the vulnerable code path to execute arbitrary code.
How to mitigate CVE-2026-63993
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/5303925e360527243b46a440a04667826bbc72b7
- https://git.kernel.org/stable/c/609e63312c29aad18026a1d3222e123d4b6b0feb
- https://git.kernel.org/stable/c/6b8bfce9d2f774d2c2243e0248e03efb99bba6c0
- https://git.kernel.org/stable/c/7d9ef0cb271555d8cf39fefe6c981e1493b25ecf
- https://git.kernel.org/stable/c/8d435d68d71fb875876b722f4136caf74f2f48bd
- https://git.kernel.org/stable/c/9257f56ac47ef1976bcd056cf986a9988eeec67a
- https://git.kernel.org/stable/c/a493efd4336cf19122ae0e4cbb3d31b32d70deea
- https://git.kernel.org/stable/c/dc3bfa050f873371e745bdf478b1f5b738e5733d