What is CVE-2026-63993?

CVE-2026-63993 is a critical-severity vulnerability in Linux. CVSS score: 9.8/10. Published 2026-07-19.

How severe is CVE-2026-63993?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Vulnerability in Linux

CVE-2026-63993

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 c…

EPSS: 0.002 (7.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Linux — versions 4cb47a8644cc9eb8ec81190a50e79e6530d0297f, 5.9, 0

References

416baaa9-dc9f-4396-8d5f-8c081fb06d67
416baaa9-dc9f-4396-8d5f-8c081fb06d67
416baaa9-dc9f-4396-8d5f-8c081fb06d67
416baaa9-dc9f-4396-8d5f-8c081fb06d67
416baaa9-dc9f-4396-8d5f-8c081fb06d67
416baaa9-dc9f-4396-8d5f-8c081fb06d67
416baaa9-dc9f-4396-8d5f-8c081fb06d67
416baaa9-dc9f-4396-8d5f-8c081fb06d67

Frequently asked questions

What is CVE-2026-63993?: CVE-2026-63993 is a critical-severity vulnerability in Linux. CVSS score: 9.8/10. Published 2026-07-19.
How severe is CVE-2026-63993?: Critical severity. CVSS v3 base score is 9.8 out of 10.