CVE-2026-45841
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nfnetlink_osf: fix divide-by-zero in OSF_WSS_MODULO nf_osf_match_one() computes ctx->window % f->wss.val in the OSF_WSS_MODULO branch with no guard for f->wss.val == 0. A CAP_NET_ADMIN user can add such a fingerprint via nfnetlink; a subsequent matching TCP SYN divides by zero and panics the kernel. Reject the bogus fingerprint in nfnl_osf_add_callback() above the per-option for-loop. f->wss is per-fingerprint, not per-option, so the check must run regardless of f->opt_num (including 0). Also reject wss.wc >= OSF_WSS_MAX; nf_osf_match_one() already treats that as "should not happen". Crash: Oops: divide error: 0000 [#1] SMP KASAN NOPTI RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98) Call Trace: <IRQ> nf_osf_match (net/netfilter/nfnetlink_osf.c:220) xt_osf_match_packet (net/netfilter/xt_osf.c:32) ipt_do_table (net/ipv4/netfilter/ip_tables.c:348) nf_hook_slow (net/netfilter/core.c:622) ip_local_deliver (net/ipv4/ip_input.c:265) ip_rcv (include/linux/skbuff.h:1162) __netif_receive_skb_one_core (net/core/dev.c:6181) process_backlog (net/core/dev.c:6642) __napi_poll (net/core/dev.c:7710) net_rx_action (net/core/dev.c:7945) handle_softirqs (kernel/softirq.c:622)
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-05-27 11:16:23.493000
Last modified
2026-11-06 16:18:46.020000
View original CVE JSON
{
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-05-27T11:16:23.493",
"lastModified": "2026-11-06T16:18:46.020",
"vulnStatus": "Modified",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nfnetlink_osf: fix divide-by-zero in OSF_WSS_MODULO\n\nnf_osf_match_one() computes ctx->window % f->wss.val in the\nOSF_WSS_MODULO branch with no guard for f->wss.val == 0. A\nCAP_NET_ADMIN user can add such a fingerprint via nfnetlink; a\nsubsequent matching TCP SYN divides by zero and panics the kernel.\n\nReject the bogus fingerprint in nfnl_osf_add_callback() above the\nper-option for-loop. f->wss is per-fingerprint, not per-option, so\nthe check must run regardless of f->opt_num (including 0). Also\nreject wss.wc >= OSF_WSS_MAX; nf_osf_match_one() already treats that\nas \"should not happen\".\n\nCrash:\n Oops: divide error: 0000 [#1] SMP KASAN NOPTI\n RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98)\n Call Trace:\n <IRQ>\n nf_osf_match (net/netfilter/nfnetlink_osf.c:220)\n xt_osf_match_packet (net/netfilter/xt_osf.c:32)\n ipt_do_table (net/ipv4/netfilter/ip_tables.c:348)\n nf_hook_slow (net/netfilter/core.c:622)\n ip_local_deliver (net/ipv4/ip_input.c:265)\n ip_rcv (include/linux/skbuff.h:1162)\n __netif_receive_skb_one_core (net/core/dev.c:6181)\n process_backlog (net/core/dev.c:6642)\n __napi_poll (net/core/dev.c:7710)\n net_rx_action (net/core/dev.c:7945)\n handle_softirqs (kernel/softirq.c:622)"
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