CVE-2025-40206netfilter: nft_objref: validate objref and objrefmap expressions
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In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_objref: validate objref and objrefmap expressions Referencing a synproxy stateful object from OUTPUT hook causes kernel crash due to infinite recursive calls: BUG: TASK stack guard page was hit at 000000008bda5b8c (stack is 000000003ab1c4a5..00000000494d8b12) [...] Call Trace: __find_rr_leaf+0x99/0x230 fib6_table_lookup+0x13b/0x2d0 ip6_pol_route+0xa4/0x400 fib6_rule_lookup+0x156/0x240 ip6_route_output_flags+0xc6/0x150 __nf_ip6_route+0x23/0x50 synproxy_send_tcp_ipv6+0x106/0x200 synproxy_send_client_synack_ipv6+0x1aa/0x1f0 nft_synproxy_do_eval+0x263/0x310 nft_do_chain+0x5a8/0x5f0 [nf_tables nft_do_chain_inet+0x98/0x110 nf_hook_slow+0x43/0xc0 __ip6_local_out+0xf0/0x170 ip6_local_out+0x17/0x70 synproxy_send_tcp_ipv6+0x1a2/0x200 synproxy_send_client_synack_ipv6+0x1aa/0x1f0 [...] Implement objref and objrefmap expression validate functions. Currently, only NFT_OBJECT_SYNPROXY object type requires validation. This will also handle a jump to a chain using a synproxy object from the OUTPUT hook. Now when trying to reference a synproxy object in the OUTPUT hook, nft will produce the following error: synproxy_crash.nft: Error: Could not process rule: Operation not supported synproxy name mysynproxy ^^^^^^^^^^^^^^^^^^^^^^^^
- CVSS
- 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Deferred
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from ee394f96ad7517fbc0de9106dcc7ce9efb14f264 before f31bcea12222a26d6f151df9c4a6d21f2eec1724; from ee394f96ad7517fbc0de9106dcc7ce9efb14f264 before 0028e0134c64d9ed21728341a74fcfc59cd0f944; from ee394f96ad7517fbc0de9106dcc7ce9efb14f264 before 7ea55a44493a5a36c3b3293b88bbe4841f9dbaf0; from ee394f96ad7517fbc0de9106dcc7ce9efb14f264 before 4c1cf72ec10be5a9ad264650cadffa1fbce6fabd; from ee394f96ad7517fbc0de9106dcc7ce9efb14f264 before f359b809d54c6e3dd1d039b97e0b68390b0e53e4 | CNA record |
References
- https://git.kernel.org/stable/c/f31bcea12222a26d6f151df9c4a6d21f2eec1724
- https://git.kernel.org/stable/c/0028e0134c64d9ed21728341a74fcfc59cd0f944
- https://git.kernel.org/stable/c/7ea55a44493a5a36c3b3293b88bbe4841f9dbaf0
- https://git.kernel.org/stable/c/4c1cf72ec10be5a9ad264650cadffa1fbce6fabd
- https://git.kernel.org/stable/c/f359b809d54c6e3dd1d039b97e0b68390b0e53e4
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.