CVE-2026-64554 in Linux
Riassunto
di VulDB • 28/07/2026
Nel kernel Linux, è stata risolta la seguente vulnerabilità:
netfilter: bridge: correggere il puntatore prevhdr obsoleto in br_ip6_fragment()
br_ip6_fragment() ottiene prevhdr, un puntamento all'interno dell'area head dello skb, da ip6_find_1stfragopt(), quindi chiama skb_checksum_help(). Per uno skb clonato (cloned), skb_checksum_help() rialloca l'area head tramite pskb_expand_head(), lasciando il puntatore prevhdr dangling. Successivamente viene dereferenziato in ip6_frag_next(), causando una scrittura use-after-free.
Salvare lo offset di prevhdr prima della chiamata a skb_checksum_help() e ricalcolarlo dopo, come fatto nel commit ef0efcd3bd3f ("ipv6: Fix dangling pointer when ipv6 fragment").
BUG: KASAN: slab-use-after-free in ip6_frag_next (net/ipv6/ip6_output.c:857) Write of size 1 at addr ffff888013ff5016 by task exploit/141 Call Trace: ... kasan_report (mm/kasan/report.c:595) ip6_frag_next (net/ipv6/ip6_output.c:857) br_ip6_fragment (net/ipv6/netfilter.c:212) nf_ct_bridge_post (net/bridge/netfilter/nf_conntrack_bridge.c:407) nf_hook_slow (net/netfilter/core.c:619) br_forward_finish (net/bridge/br_forward.c:66) __br_forward (net/bridge/br_forward.c:115) maybe_deliver (net/bridge/br_forward.c:191) br_flood (net/bridge/br_forward.c:245) br_handle_frame_finish (net/bridge/br_input.c:229) br_handle_frame (net/bridge/br_input.c:442) ... packet_sendmsg (net/packet/af_packet.c:3114) ... do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Kernel panic - not syncing: Fatal exception in interrupt
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