CVE-2026-63993

Summary

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 Software

VendorProductVersion RangeStatus
LinuxLinux4cb47a8644cc9eb8ec81190a50e79e6530d0297f < 6b8bfce9d2f774d2c2243e0248e03efb99bba6c0affected
LinuxLinux4cb47a8644cc9eb8ec81190a50e79e6530d0297f < 9257f56ac47ef1976bcd056cf986a9988eeec67aaffected
LinuxLinux4cb47a8644cc9eb8ec81190a50e79e6530d0297f < 8d435d68d71fb875876b722f4136caf74f2f48bdaffected
LinuxLinux4cb47a8644cc9eb8ec81190a50e79e6530d0297f < dc3bfa050f873371e745bdf478b1f5b738e5733daffected
LinuxLinux4cb47a8644cc9eb8ec81190a50e79e6530d0297f < 609e63312c29aad18026a1d3222e123d4b6b0febaffected
LinuxLinux4cb47a8644cc9eb8ec81190a50e79e6530d0297f < 5303925e360527243b46a440a04667826bbc72b7affected
LinuxLinux4cb47a8644cc9eb8ec81190a50e79e6530d0297f < a493efd4336cf19122ae0e4cbb3d31b32d70deeaaffected
LinuxLinux4cb47a8644cc9eb8ec81190a50e79e6530d0297f < 7d9ef0cb271555d8cf39fefe6c981e1493b25ecfaffected
LinuxLinux5.9affected
LinuxLinux0 < 5.9unaffected
LinuxLinux5.10.259 <= 5.10.*unaffected
LinuxLinux5.15.210 <= 5.15.*unaffected
LinuxLinux6.1.176 <= 6.1.*unaffected
LinuxLinux6.6.143 <= 6.6.*unaffected
LinuxLinux6.12.93 <= 6.12.*unaffected
LinuxLinux6.18.35 <= 6.18.*unaffected
LinuxLinux7.0.12 <= 7.0.*unaffected
LinuxLinux7.1 <= *unaffected

Weaknesses

References