CVE-2025-40206: netfilter: nft_objref: validate objref and objrefmap expressions

Published Nov 12, 2025
·
Updated

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nftobjref: 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: findrrleaf+0x99/0x230 fib6tablelookup+0x13b/0x2d0 ip6polroute+0xa4/0x400 fib6rulelookup+0x156/0x240 ip6routeoutputflags+0xc6/0x150 nfip6route+0x23/0x50 synproxysendtcpipv6+0x106/0x200 synproxysendclientsynackipv6+0x1aa/0x1f0 nftsynproxydoeval+0x263/0x310 nftdochain+0x5a8/0x5f0 [nftables nftdochaininet+0x98/0x110 nfhookslow+0x43/0xc0 ip6localout+0xf0/0x170 ip6localout+0x17/0x70 synproxysendtcpipv6+0x1a2/0x200 synproxysendclientsynackipv6+0x1aa/0x1f0 [...]

Implement objref and objrefmap expression validate functions.

Currently, only NFTOBJECTSYNPROXY 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:

synproxycrash.nft: Error: Could not process rule: Operation not supported synproxy name mysynproxy ^^^^^^^^^^^^^^^^^^^^^^^^

Affected Software

214 affected componentsFixes available
Linux Linux kernel
Microsoft azl3 kernel 6.6.112.1-2
Patch available
ubuntu/linux-hwe-edge*
ubuntu/linux-aws-5.0*
ubuntu/linux-aws-5.3*
ubuntu/linux-aws-5.4*
ubuntu/linux-azure*
ubuntu/linux-azure-5.3*
ubuntu/linux-azure-5.4*
ubuntu/linux-azure-edge*
ubuntu/linux-gcp*
ubuntu/linux-gcp-5.3*
ubuntu/linux-gcp-5.4*
ubuntu/linux-gke-4.15*
ubuntu/linux-gke-5.4*
ubuntu/linux-gkeop-5.4*
ubuntu/linux-hwe*
ubuntu/linux-hwe-5.4*
ubuntu/linux-hwe-edge*
ubuntu/linux-ibm-5.4*
ubuntu/linux-oem*
ubuntu/linux-oracle-5.0*
ubuntu/linux-oracle-5.3*
ubuntu/linux-oracle-5.4*
ubuntu/linux-raspi-5.4*
ubuntu/linux*
ubuntu/linux-aws*
ubuntu/linux-aws-5.11*
ubuntu/linux-aws-5.13*
ubuntu/linux-aws-5.15*
ubuntu/linux-aws-5.8*
ubuntu/linux-azure*
ubuntu/linux-azure-5.11*
ubuntu/linux-azure-5.13*
ubuntu/linux-azure-5.15*
ubuntu/linux-azure-5.8*
ubuntu/linux-azure-fde*
ubuntu/linux-azure-fde-5.15*
ubuntu/linux-bluefield*
ubuntu/linux-gcp*
ubuntu/linux-gcp-5.11*
ubuntu/linux-gcp-5.13*
ubuntu/linux-gcp-5.15*
ubuntu/linux-gcp-5.8*
ubuntu/linux-gke*
ubuntu/linux-gke-5.15*
ubuntu/linux-gkeop*
ubuntu/linux-gkeop-5.15*
ubuntu/linux-hwe-5.11*
ubuntu/linux-hwe-5.13*
ubuntu/linux-hwe-5.15*
ubuntu/linux-hwe-5.8*
ubuntu/linux-ibm*
ubuntu/linux-ibm-5.15*
ubuntu/linux-intel-5.13*
ubuntu/linux-intel-iotg-5.15*
ubuntu/linux-iot*
ubuntu/linux-kvm*
ubuntu/linux-lowlatency-hwe-5.15*
ubuntu/linux-nvidia-tegra-5.15*
ubuntu/linux-oem-5.10*
ubuntu/linux-oem-5.13*
ubuntu/linux-oem-5.6*
ubuntu/linux-oracle*
ubuntu/linux-oracle-5.11*
ubuntu/linux-oracle-5.13*
ubuntu/linux-oracle-5.15*
ubuntu/linux-oracle-5.8*
ubuntu/linux-raspi*
ubuntu/linux-raspi2*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.11*
ubuntu/linux-riscv-5.15*
ubuntu/linux-riscv-5.8*
ubuntu/linux-xilinx-zynqmp*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux*
ubuntu/linux-allwinner-5.19*
ubuntu/linux-aws*
ubuntu/linux-aws-5.19*
ubuntu/linux-aws-6.2*
ubuntu/linux-aws-6.5*
ubuntu/linux-aws-6.8<6.8.0-1050.53~22.04.1
6.8.0-1050.53~22.04.1
ubuntu/linux-azure*
ubuntu/linux-azure-5.19*
ubuntu/linux-azure-6.2*
ubuntu/linux-azure-6.5*
ubuntu/linux-azure-6.8<6.8.0-1051.57~22.04.1
6.8.0-1051.57~22.04.1
ubuntu/linux-azure-fde*
ubuntu/linux-azure-fde-5.19*
ubuntu/linux-azure-fde-6.2*
ubuntu/linux-azure-fde-6.8<6.8.0-1058.65~22.04.1
6.8.0-1058.65~22.04.1
ubuntu/linux-gcp*
ubuntu/linux-gcp-5.19*
ubuntu/linux-gcp-6.2*
ubuntu/linux-gcp-6.5*
ubuntu/linux-gcp-6.8<6.8.0-1052.55~22.04.1
6.8.0-1052.55~22.04.1
ubuntu/linux-gke*
ubuntu/linux-gkeop*
ubuntu/linux-hwe-5.19*
ubuntu/linux-hwe-6.2*
ubuntu/linux-hwe-6.5*
ubuntu/linux-hwe-6.8<6.8.0-106.106~22.04.1
6.8.0-106.106~22.04.1
ubuntu/linux-ibm*
ubuntu/linux-ibm-6.8<6.8.0-1049.49~22.04.1
6.8.0-1049.49~22.04.1
ubuntu/linux-intel-iot-realtime*
ubuntu/linux-intel-iotg*
ubuntu/linux-kvm*
ubuntu/linux-lowlatency*
ubuntu/linux-lowlatency-hwe-5.19*
ubuntu/linux-lowlatency-hwe-6.2*
ubuntu/linux-lowlatency-hwe-6.5*
ubuntu/linux-lowlatency-hwe-6.8<6.8.0-106.106.1~22.04.1
6.8.0-106.106.1~22.04.1
ubuntu/linux-nvidia*
ubuntu/linux-nvidia-6.2*
ubuntu/linux-nvidia-6.5*
ubuntu/linux-nvidia-6.8<6.8.0-1049.52~22.04.1
6.8.0-1049.52~22.04.1
ubuntu/linux-nvidia-tegra*
ubuntu/linux-nvidia-tegra-igx*
ubuntu/linux-oem-5.17*
ubuntu/linux-oem-6.0*
ubuntu/linux-oem-6.1*
ubuntu/linux-oem-6.5*
ubuntu/linux-oracle*
ubuntu/linux-oracle-6.5*
ubuntu/linux-oracle-6.8<6.8.0-1047.48~22.04.1
6.8.0-1047.48~22.04.1
ubuntu/linux-raspi*
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.19*
ubuntu/linux-riscv-6.5*
ubuntu/linux-riscv-6.8<6.8.0-106.106~22.04.1
6.8.0-106.106~22.04.1
ubuntu/linux-starfive-5.19*
ubuntu/linux-starfive-6.2*
ubuntu/linux-starfive-6.5*
ubuntu/linux-xilinx-zynqmp*
ubuntu/linux-bluefield*
ubuntu/linux-intel-iot-realtime*
ubuntu/linux-realtime*
ubuntu/linux-realtime-6.8<6.8.1-1045.46~22.04.1
6.8.1-1045.46~22.04.1
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<6.8.0-106.106
6.8.0-106.106
ubuntu/linux-aws<6.8.0-1050.53
6.8.0-1050.53
ubuntu/linux-aws-6.14*
ubuntu/linux-aws-6.17<6.17.0-1007.7~24.04.1
6.17.0-1007.7~24.04.1
ubuntu/linux-azure<6.8.0-1051.57
6.8.0-1051.57
ubuntu/linux-azure-6.11*
ubuntu/linux-azure-6.14*
ubuntu/linux-azure-fde<6.8.0-1058.65
6.8.0-1058.65
ubuntu/linux-azure-fde-6.14*
ubuntu/linux-azure-nvidia<6.8.0-1039.42
6.8.0-1039.42
ubuntu/linux-azure-nvidia-6.14*
ubuntu/linux-gcp<6.8.0-1052.55
6.8.0-1052.55
ubuntu/linux-gcp-6.11*
ubuntu/linux-gcp-6.14*
ubuntu/linux-gcp-6.17<6.17.0-1008.8~24.04.1
6.17.0-1008.8~24.04.1
ubuntu/linux-gke<6.8.0-1048.53
6.8.0-1048.53
ubuntu/linux-gkeop<6.8.0-1035.38
6.8.0-1035.38
ubuntu/linux-hwe-6.11*
ubuntu/linux-hwe-6.14*
ubuntu/linux-ibm<6.8.0-1049.49
6.8.0-1049.49
ubuntu/linux-lowlatency<6.8.0-106.106.1
6.8.0-106.106.1
ubuntu/linux-lowlatency-hwe-6.11*
ubuntu/linux-nvidia<6.8.0-1049.52
6.8.0-1049.52
ubuntu/linux-nvidia-6.11*
ubuntu/linux-nvidia-6.17<6.17.0-1008.8
6.17.0-1008.8
ubuntu/linux-nvidia-lowlatency<6.8.0-1049.52.1
6.8.0-1049.52.1
ubuntu/linux-nvidia-tegra<6.8.0-1020.20
6.8.0-1020.20
ubuntu/linux-oem-6.11*
ubuntu/linux-oem-6.14*
ubuntu/linux-oem-6.17<6.17.0-1011.11
6.17.0-1011.11
ubuntu/linux-oem-6.8*
ubuntu/linux-oracle<6.8.0-1047.48
6.8.0-1047.48
ubuntu/linux-oracle-6.14*
ubuntu/linux-oracle-6.17<6.17.0-1007.7~24.04.1
6.17.0-1007.7~24.04.1
ubuntu/linux-raspi<6.8.0-1050.54
6.8.0-1050.54
ubuntu/linux-raspi-realtime*
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-riscv-6.14*
ubuntu/linux-xilinx<6.8.0-1028.29
6.8.0-1028.29
ubuntu/linux-bluefield<6.8.0-1017.21
6.8.0-1017.21
ubuntu/linux-raspi-realtime<6.8.0-2040.41
6.8.0-2040.41
ubuntu/linux-realtime<6.8.1-1045.46
6.8.1-1045.46
ubuntu/linux-realtime-6.14*
ubuntu/linux-realtime-6.17<6.17.0-1006.7~24.04.1
6.17.0-1006.7~24.04.1
ubuntu/linux-aws-fips<6.8.0-1050.53+fips1
6.8.0-1050.53+fips1
ubuntu/linux-azure-fips<6.8.0-1052.58+fips1
6.8.0-1052.58+fips1
ubuntu/linux-fips<6.8.0-106.106+fips1
6.8.0-106.106+fips1
ubuntu/linux-gcp-fips<6.8.0-1052.55+fips1
6.8.0-1052.55+fips1
ubuntu/linux<6.17.0-14.14
6.17.0-14.14
ubuntu/linux-aws<6.17.0-1007.7
6.17.0-1007.7
ubuntu/linux-azure<6.17.0-1008.8
6.17.0-1008.8
ubuntu/linux-azure-fde*
ubuntu/linux-gcp<6.17.0-1007.7
6.17.0-1007.7
ubuntu/linux-oracle<6.17.0-1007.7
6.17.0-1007.7
ubuntu/linux-raspi<6.17.0-1008.8
6.17.0-1008.8
ubuntu/linux-realtime<6.17.0-1006.7
6.17.0-1006.7
ubuntu/linux-riscv<6.17.0-14.14.1
6.17.0-14.14.1
ubuntu/linux-vmware*

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade ubuntu/linux-aws-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1050.53~22.04.1
  2. Upgrade

    Upgrade ubuntu/linux-azure-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1051.57~22.04.1
  3. Upgrade

    Upgrade ubuntu/linux-azure-fde-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1058.65~22.04.1
  4. Upgrade

    Upgrade ubuntu/linux-gcp-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1052.55~22.04.1
  5. Upgrade

    Upgrade ubuntu/linux-hwe-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-106.106~22.04.1
  6. Upgrade

    Upgrade ubuntu/linux-ibm-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1049.49~22.04.1
  7. Upgrade

    Upgrade ubuntu/linux-lowlatency-hwe-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-106.106.1~22.04.1
  8. Upgrade

    Upgrade ubuntu/linux-nvidia-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1049.52~22.04.1
  9. Upgrade

    Upgrade ubuntu/linux-oracle-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1047.48~22.04.1
  10. Upgrade

    Upgrade ubuntu/linux-riscv-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-106.106~22.04.1
  11. Upgrade

    Upgrade ubuntu/linux-realtime-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.1-1045.46~22.04.1
  12. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 6.8.0-106.106
  13. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 6.8.0-1050.53
  14. Upgrade

    Upgrade ubuntu/linux-aws-6.17 to a version that resolves this vulnerability.

    Fixed in 6.17.0-1007.7~24.04.1
  15. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 6.8.0-1051.57
  16. Upgrade

    Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.

    Fixed in 6.8.0-1058.65
  17. Upgrade

    Upgrade ubuntu/linux-azure-nvidia to a version that resolves this vulnerability.

    Fixed in 6.8.0-1039.42
  18. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 6.8.0-1052.55
  19. Upgrade

    Upgrade ubuntu/linux-gcp-6.17 to a version that resolves this vulnerability.

    Fixed in 6.17.0-1008.8~24.04.1
  20. Upgrade

    Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.

    Fixed in 6.8.0-1048.53
  21. Upgrade

    Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.

    Fixed in 6.8.0-1035.38
  22. Upgrade

    Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.

    Fixed in 6.8.0-1049.49
  23. Upgrade

    Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.

    Fixed in 6.8.0-106.106.1
  24. Upgrade

    Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.

    Fixed in 6.8.0-1049.52
  25. Upgrade

    Upgrade ubuntu/linux-nvidia-6.17 to a version that resolves this vulnerability.

    Fixed in 6.17.0-1008.8
  26. Upgrade

    Upgrade ubuntu/linux-nvidia-lowlatency to a version that resolves this vulnerability.

    Fixed in 6.8.0-1049.52.1
  27. Upgrade

    Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.

    Fixed in 6.8.0-1020.20
  28. Upgrade

    Upgrade ubuntu/linux-oem-6.17 to a version that resolves this vulnerability.

    Fixed in 6.17.0-1011.11
  29. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 6.8.0-1047.48
  30. Upgrade

    Upgrade ubuntu/linux-oracle-6.17 to a version that resolves this vulnerability.

    Fixed in 6.17.0-1007.7~24.04.1
  31. Upgrade

    Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.

    Fixed in 6.8.0-1050.54
  32. Upgrade

    Upgrade ubuntu/linux-xilinx to a version that resolves this vulnerability.

    Fixed in 6.8.0-1028.29
  33. Upgrade

    Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.

    Fixed in 6.8.0-1017.21
  34. Upgrade

    Upgrade ubuntu/linux-raspi-realtime to a version that resolves this vulnerability.

    Fixed in 6.8.0-2040.41
  35. Upgrade

    Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.

    Fixed in 6.8.1-1045.46
  36. Upgrade

    Upgrade ubuntu/linux-realtime-6.17 to a version that resolves this vulnerability.

    Fixed in 6.17.0-1006.7~24.04.1
  37. Upgrade

    Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.

    Fixed in 6.8.0-1050.53+fips1
  38. Upgrade

    Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.

    Fixed in 6.8.0-1052.58+fips1
  39. Upgrade

    Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.

    Fixed in 6.8.0-106.106+fips1
  40. Upgrade

    Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.

    Fixed in 6.8.0-1052.55+fips1
  41. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 6.17.0-14.14
  42. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 6.17.0-1007.7
  43. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 6.17.0-1008.8
  44. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 6.17.0-1007.7
  45. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 6.17.0-1007.7
  46. Upgrade

    Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.

    Fixed in 6.17.0-1008.8
  47. Upgrade

    Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.

    Fixed in 6.17.0-1006.7
  48. Upgrade

    Upgrade ubuntu/linux-riscv to a version that resolves this vulnerability.

    Fixed in 6.17.0-14.14.1
  49. Compensating control

    Do not reference synproxy stateful objects from the OUTPUT hook, including through a jump to a chain that uses a synproxy object.

Event History

Nov 12, 2025
CVE Published
via MITRE·09:56 PM
Data Sourced
via MITRE·09:56 PM
DescriptionSeverity
Data Sourced
via OSV·10:15 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·10:15 PM
DescriptionSeverity
Nov 14, 2025
Data Sourced
via Microsoft·01:02 AM
DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

What is the severity of CVE-2025-40206?

The severity of CVE-2025-40206 is considered high due to the potential for kernel crashes.

2

How does CVE-2025-40206 affect the Linux kernel?

CVE-2025-40206 causes kernel crashes due to infinite recursive calls when referencing a synproxy stateful object from the OUTPUT hook.

3

How do I fix CVE-2025-40206?

To fix CVE-2025-40206, update the Linux kernel to the latest patched version.

4

What are the symptoms of CVE-2025-40206 exploitation?

Symptoms of exploitation of CVE-2025-40206 include unexpected kernel crashes and instability in the system.

5

Is CVE-2025-40206 present in all versions of the Linux kernel?

CVE-2025-40206 affects specific versions of the Linux kernel, so checking the installed version is crucial.

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