Critical severity · published Jul 19, 2026
CVE-2026-63993
vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()
9.8
CVSS
0.5%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 44% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KE
Kernel · Linux
5.9 before 5.10.259; 5.11 before 5.15.210; 5.16 before 6.1.176; 6.2 before 6.6.143; 6.7 before 6.12.93; 6.13 before 6.18.35; +6 more · source: NVD
LI
Linux · Linux
4cb47a8644cc9eb8ec81190a50e79e6530d0297f before 6b8bfce9d2f774d2c2243e0248e03efb99bba6c0; 4cb47a8644cc9eb8ec81190a50e79e6530d0297f before 9257f56ac47ef1976bcd056cf986a9988eeec67a; 4cb47a8644cc9eb8ec81190a50e79e6530d0297f before 8d435d68d71fb875876b722f4136caf74f2f48bd; 4cb47a8644cc9eb8ec81190a50e79e6530d0297f before dc3bfa050f873371e745bdf478b1f5b738e5733d; 4cb47a8644cc9eb8ec81190a50e79e6530d0297f before 609e63312c29aad18026a1d3222e123d4b6b0feb; 4cb47a8644cc9eb8ec81190a50e79e6530d0297f before 5303925e360527243b46a440a04667826bbc72b7; +3 more · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-63993
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-63993
Patch
https://git.kernel.org/stable/c/5303925e360527243b46a440a04667826bbc72b7
Patch
https://git.kernel.org/stable/c/609e63312c29aad18026a1d3222e123d4b6b0feb
Patch
https://git.kernel.org/stable/c/6b8bfce9d2f774d2c2243e0248e03efb99bba6c0
Patch
https://git.kernel.org/stable/c/7d9ef0cb271555d8cf39fefe6c981e1493b25ecf
Patch
https://git.kernel.org/stable/c/8d435d68d71fb875876b722f4136caf74f2f48bd
Patch
https://git.kernel.org/stable/c/9257f56ac47ef1976bcd056cf986a9988eeec67a
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