In the Linux kernel, the following vulnerability has been resolved: vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()… (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 cause an UAF. Use instead ip_hdr(skb) as done in drivers/net/bareudp.c and drivers/net/geneve.c. Found by Sashiko.
AI Analysis
Technical Summary
The vulnerability in the Linux kernel's VXLAN code involves reusing a cached ip_hdr() pointer after a call to skb_tunnel_check_pmtu(), which can alter skb->head. This leads to a use-after-free condition due to stale pointer usage. The resolution replaces the cached pointer with a fresh call to ip_hdr(skb) after skb_tunnel_check_pmtu(), aligning with practices in other network drivers like bareudp and geneve.
Potential Impact
The vulnerability can cause use-after-free memory corruption in the Linux kernel networking stack, specifically in VXLAN processing. This could potentially lead to kernel crashes or other undefined behavior. No known exploits in the wild have been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since this is a kernel vulnerability, applying the official Linux kernel updates when available is recommended to address this issue.
In the Linux kernel, the following vulnerability has been resolved: vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()… (CVE-2026-63993)
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.
CVSS v3.1
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in the Linux kernel's VXLAN code involves reusing a cached ip_hdr() pointer after a call to skb_tunnel_check_pmtu(), which can alter skb->head. This leads to a use-after-free condition due to stale pointer usage. The resolution replaces the cached pointer with a fresh call to ip_hdr(skb) after skb_tunnel_check_pmtu(), aligning with practices in other network drivers like bareudp and geneve.
Potential Impact
The vulnerability can cause use-after-free memory corruption in the Linux kernel networking stack, specifically in VXLAN processing. This could potentially lead to kernel crashes or other undefined behavior. No known exploits in the wild have been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since this is a kernel vulnerability, applying the official Linux kernel updates when available is recommended to address this issue.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-p6vc-4hvx-xvcw
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-63993"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a5d27aa2a4a8d598912dbea
Added to database: 07/19/2026, 19:38:18 UTC
Last enriched: 07/19/2026, 20:01:06 UTC
Last updated: 07/20/2026, 21:51:19 UTC
Views: 12
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