Linux Kernel up to 6.6.112/6.12.53/6.17.3 nft_objref state issue

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel up to 6.6.112/6.12.53/6.17.3. This affects the function nft_objref. The manipulation results in state issue. This vulnerability is cataloged as CVE-2025-40206. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.6.112/6.12.53/6.17.3. Affected is the function nft_objref. The manipulation with an unknown input leads to a state issue vulnerability. CWE is classifying the issue as CWE-371. The impact remains unknown. CVE summarizes:

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 ^^^^^^^^^^^^^^^^^^^^^^^^

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2025-40206 since 04/16/2025. The exploitability is told to be difficult. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 02/07/2026).

The vulnerability scanner Nessus provides a plugin with the ID 275351 (Linux Distros Unpatched Vulnerability : CVE-2025-40206), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.113, 6.12.54, 6.17.4 or 6.18-rc1 eliminates this vulnerability. Applying the patch 0028e0134c64d9ed21728341a74fcfc59cd0f944/7ea55a44493a5a36c3b3293b88bbe4841f9dbaf0/4c1cf72ec10be5a9ad264650cadffa1fbce6fabd/f359b809d54c6e3dd1d039b97e0b68390b0e53e4 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (275351) and CERT Bund (WID-SEC-2025-2595). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• Open Source Linux Kernel
• RESF Rocky Linux

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.6.112
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
• 6.12.9
• 6.12.10
• 6.12.11
• 6.12.12
• 6.12.13
• 6.12.14
• 6.12.15
• 6.12.16
• 6.12.17
• 6.12.18
• 6.12.19
• 6.12.20
• 6.12.21
• 6.12.22
• 6.12.23
• 6.12.24
• 6.12.25
• 6.12.26
• 6.12.27
• 6.12.28
• 6.12.29
• 6.12.30
• 6.12.31
• 6.12.32
• 6.12.33
• 6.12.34
• 6.12.35
• 6.12.36
• 6.12.37
• 6.12.38
• 6.12.39
• 6.12.40
• 6.12.41
• 6.12.42
• 6.12.43
• 6.12.44
• 6.12.45
• 6.12.46
• 6.12.47
• 6.12.48
• 6.12.49
• 6.12.50
• 6.12.51
• 6.12.52
• 6.12.53
• 6.17.0
• 6.17.1
• 6.17.2
• 6.17.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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