CVE-2026-63993 Details
Description
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.
A use-after-free vulnerability has been identified in the Linux kernel's VXLAN implementation. The issue arises from the improper handling of the IP header after performing Path Maximum Transmission Unit (PMTU) checks. Specifically, the function 'skb_tunnel_check_pmtu()' can modify the socket buffer's header, and reusing the cached IP header value can lead to a use-after-free condition. This vulnerability affects the Linux kernel's stable group.
Users can upgrade to the latest version of the Linux kernel where this vulnerability has been patched. Instructions for downloading the patched version are available on the official Linux kernel website.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
No SSVC data is available for this CVE.
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Weakness Enumeration
No weakness enumeration is available for this CVE.
Affected Products
No affected product data is available for this CVE.
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 20, 2026 | CVE Modified | kernel.org |
| Jul 19, 2026 | New CVE Received | kernel.org |