In the Linux kernel, the following vulnerability has been resolved:
netfilter: nft_inner: Fix IPv6 inner_thoff desync
In nft_inner_parse_l2l3(), when processing inner IPv6 packets, ipv6_find_hdr() correctly computes the transport header offset traversing all extension headers, but the result is immediately overwritten with nhoff + sizeof(_ip6h) (40 bytes), which only accounts for the IPv6 base header. This creates a desync between inner_thoff (wrong — points to extension header start) and l4proto (correct — e.g., IPPROTO_TCP), enabling transport header forgery and potential firewall bypass. This issue affects stable versions from Linux 6.2.
For comparison, the normal (non-inner) IPv6 path correctly preserves ipv6_find_hdr()'s result. Removing the incorrect overwrite ensures that ipv6_find_hdr()'s calculated transport header offset is preserved, thereby fixing the desynchronization.
Exploitability
AV:LAC:LPR:LUI:NScope
S:UImpact
C:HI:LA:H7.3/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H