CVE-2026-45841: Linux kernel · netfilter: nfnetlink_osf: fix divide-by-zero in OSF_WSS_MODULO
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in fb965b1cfe92b28d28b5ebe3116b81dbef9f2d2f : update Linux kernel when convenient.
Data as of 6 Nov 2026, 16:04 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-06.
- Patch
- Available – fixed in fb965b1cfe92b28d28b5ebe3116b81dbef9f2d2f, cb833bbc1b3c51e08652d3c86298307c07d3f2db, c55940895245d8ef658ab381248a28755218d625 +5
Exploitation evidence
Disclosed: evidence found.
CVE published 27 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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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)
References
- git.kernel.org/stable/c/cb833bbc1b3c51e08652d3c86298307c07d3f2db (opens in a new tab)
- git.kernel.org/stable/c/26900306a5a2c3e4f75c643a064525526bb6e5f3 (opens in a new tab)
- git.kernel.org/stable/c/0694618cf3e9b120666e31f5f383a6e466d95a0d (opens in a new tab)
- git.kernel.org/stable/c/8def8fbd23f40e945febe913d04b731012ce0082 (opens in a new tab)
- git.kernel.org/stable/c/c55940895245d8ef658ab381248a28755218d625 (opens in a new tab)
- git.kernel.org/stable/c/fb965b1cfe92b28d28b5ebe3116b81dbef9f2d2f (opens in a new tab)
- git.kernel.org/stable/c/9a05e195618a6d474f2bcd5b6376d0ffc2f00366 (opens in a new tab)
- git.kernel.org/stable/c/2195574dc6d9017d32ac346987e12659f931d932 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)