Critical severity9.8NVD Advisory· Published Jul 19, 2026· Updated Jul 30, 2026
CVE-2026-63993
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.
Affected products
3Patches
Vulnerability mechanics
References
8- git.kernel.org/stable/c/5303925e360527243b46a440a04667826bbc72b7nvd
- git.kernel.org/stable/c/609e63312c29aad18026a1d3222e123d4b6b0febnvd
- git.kernel.org/stable/c/6b8bfce9d2f774d2c2243e0248e03efb99bba6c0nvd
- git.kernel.org/stable/c/7d9ef0cb271555d8cf39fefe6c981e1493b25ecfnvd
- git.kernel.org/stable/c/8d435d68d71fb875876b722f4136caf74f2f48bdnvd
- git.kernel.org/stable/c/9257f56ac47ef1976bcd056cf986a9988eeec67anvd
- git.kernel.org/stable/c/a493efd4336cf19122ae0e4cbb3d31b32d70deeanvd
- git.kernel.org/stable/c/dc3bfa050f873371e745bdf478b1f5b738e5733dnvd
News mentions
1- Linux Kernel: 17 Vulnerabilities Across Subsystems Disclosed and Patched TogetherVypr Intelligence · Jul 20, 2026