Use-after-free in Linux kernel - CVE-2026-63993

Vulnerability identifier: #VU138657

CSH Severity: Low

CVSS v4: 8.5 [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]

CVE-ID: CVE-2026-63993

CWE-ID: CWE-416

Exploitation vector: Local access

Exploit availability: No public exploit available

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.

Linux kernel
openEuler
Ubuntu
kernel-debuginfo
python3-perf-debuginfo
python3-perf
perf-debuginfo
perf
kernel-tools-devel
kernel-tools-debuginfo
kernel-tools
kernel-source
kernel-headers
kernel-extra-modules
kernel-devel
kernel-debugsource
bpftool-debuginfo
bpftool
kernel
linux-ibm (Ubuntu package)
linux-aws (Ubuntu package)
linux-azure (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-nvidia-bos (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
kernel-debuginfo - update to 6.6.0-145.3.29.160
python3-perf-debuginfo - update to 6.6.0-145.3.29.160
python3-perf - update to 6.6.0-145.3.29.160
perf-debuginfo - update to 6.6.0-145.3.29.160
perf - update to 6.6.0-145.3.29.160
kernel-tools-devel - update to 6.6.0-145.3.29.160
kernel-tools-debuginfo - update to 6.6.0-145.3.29.160
kernel-tools - update to 6.6.0-145.3.29.160
kernel-source - update to 6.6.0-145.3.29.160
kernel-headers - update to 6.6.0-145.3.29.160
kernel-extra-modules - update to 6.6.0-145.3.29.160
kernel-devel - update to 6.6.0-145.3.29.160
kernel-debugsource - update to 6.6.0-145.3.29.160
bpftool-debuginfo - update to 6.6.0-145.3.29.160
bpftool - update to 6.6.0-145.3.29.160
kernel - update to 6.6.0-145.3.29.160
linux-ibm (Ubuntu package) - addressed in versions 7.0.0-1008.8, 7.0.0-1010.10
linux-aws (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1015.15
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1009.9, 7.0.0-1010.10
linux-nvidia (Ubuntu package) - addressed in versions 7.0.0-1016.16, 7.0.0-1016.16~24.04.1
linux-nvidia-bos (Ubuntu package) - update to 7.0.0-2016.16

• 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

• Use-after-free in Linux kernel net vxlan driver
• Ubuntu update for linux-ibm
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws
• Ubuntu update for linux-nvidia-bos
• Ubuntu update for linux-nvidia
• openEuler 24.03 LTS SP3 update for kernel