CVE-2026-23397

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> nfnetlink_osf: validate individual option lengths in fingerprints<br /> <br /> nfnl_osf_add_callback() validates opt_num bounds and string<br /> NUL-termination but does not check individual option length fields.<br /> A zero-length option causes nf_osf_match_one() to enter the option<br /> matching loop even when foptsize sums to zero, which matches packets<br /> with no TCP options where ctx-&gt;optp is NULL:<br /> <br /> Oops: general protection fault<br /> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]<br /> RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98)<br /> Call Trace:<br /> nf_osf_match (net/netfilter/nfnetlink_osf.c:227)<br /> xt_osf_match_packet (net/netfilter/xt_osf.c:32)<br /> ipt_do_table (net/ipv4/netfilter/ip_tables.c:293)<br /> nf_hook_slow (net/netfilter/core.c:623)<br /> ip_local_deliver (net/ipv4/ip_input.c:262)<br /> ip_rcv (net/ipv4/ip_input.c:573)<br /> <br /> Additionally, an MSS option (kind=2) with length