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CVE REMEDIATION GUIDE
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CVE-2025-40206 remediation guide

Linux

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...

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Research in progress

A verified fixed-version field is not available. Use the linked NVD and supporting references, then confirm the vendor-supported path before changing production systems.

ProductLinux
Affected versions>= ee394f96ad7517fbc0de9106dcc7ce9efb14f264 < 0028e0134c64d9ed21728341a74fcfc59cd0f944, >= ee394f96ad7517fbc0de9106dcc7ce9efb14f264 < 7ea55a44493a5a36c3b3293b88bbe4841f9dbaf0, >= ee394f96ad7517fbc0de9106dcc7ce9efb14f264 < 4c1cf72ec10be5a9ad264650cadffa1fbce6fabd, >= ee394f96ad7517fbc0de9106dcc7ce9efb14f264 < f359b809d54c6e3dd1d039b97e0b68390b0e53e4, >= 5.4
Fixed versionsNo verified fixed-version field is available yet
Priority basisReview · CVSS 7.8 · EPSS 0.14%
01

Identify the affected asset

Confirm whether Linux is installed, record the deployed version and installation path, and identify exposed interfaces.

  • Record the product name, package or appliance identifier, and installed version.
  • Identify internet-facing, administrative, API, and internal access paths.
  • Preserve the pre-change configuration and relevant service logs.
02

Validate the affected-version match

Compare the deployed version with the affected range: >= ee394f96ad7517fbc0de9106dcc7ce9efb14f264 < 0028e0134c64d9ed21728341a74fcfc59cd0f944, >= ee394f96ad7517fbc0de9106dcc7ce9efb14f264 < 7ea55a44493a5a36c3b3293b88bbe4841f9dbaf0, >= ee394f96ad7517fbc0de9106dcc7ce9efb14f264 < 4c1cf72ec10be5a9ad264650cadffa1fbce6fabd, >= ee394f96ad7517fbc0de9106dcc7ce9efb14f264 < f359b809d54c6e3dd1d039b97e0b68390b0e53e4, >= 5.4. Treat incomplete inventory results as unresolved.

03

Prioritize with independent signals

The CVSS severity warrants an early asset and exposure review. Combine this signal with asset criticality, exposure, compensating controls, and business impact.

04

Apply supported remediation

Follow the vendor advisory or supported update path. Current fixed-version status: No verified fixed-version field is available yet. Preserve configuration and rollback material before change.

05

Verify the result

Confirm the resulting version, service health, authentication and access paths, monitoring coverage, and relevant security logs.

  • Confirm the expected version and package state.
  • Run a functional health check for critical service paths.
  • Review authentication, error, application, and security monitoring logs.
  • Reassess exposure if the supported fix cannot be applied.

Operational boundary

This page does not replace the vendor advisory, support contract, change-management process, or recovery plan. Do not infer that an asset is unaffected from an incomplete inventory query or a missing fixed-version field.