CVE-2026-63993CWE-416

CVE-2026-63993

Critical · published July 19, 2026

CVSS v3.1
9.8
EPSS
1%
Percentile
42.9
In the wild
Unconfirmed
What it is

In the Linux kernel, the following vulnerability has been resolved:

vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()

skb_tunnel_check_pmtu() can change skb->head.

Reusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF.

Use instead ip_hdr(skb) as done in drivers/net/bareudp.c

and drivers/net/geneve.c.

Found by Sashiko.

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00514 · 42.9th percentile
Weakness
CWE-416 · Use After Free
Published
2026-07-19T20:17Z
Affected products (12)
ProductVersionsFixed in
linux/linux_kernel≥ 5.9, < 5.10.2595.10.259
linux/linux_kernel≥ 5.11, < 5.15.2105.15.210
linux/linux_kernel≥ 5.16, < 6.1.1766.1.176
linux/linux_kernel≥ 6.2, < 6.6.1436.6.143
linux/linux_kernel≥ 6.7, < 6.12.936.12.93
linux/linux_kernel≥ 6.13, < 6.18.356.18.35
linux/linux_kernel≥ 6.19, < 7.0.127.0.12
linux/linux_kernelall versions—
linux/linux_kernelall versions—
linux/linux_kernelall versions—
linux/linux_kernelall versions—
linux/linux_kernelall versions—
References (8)
EPSS history
Timeline
  • 19 JUL 14:56Z
    vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()
    cvelistv5