In the Linux kernel, the following vulnerability has been resolved: netfilter: socket: Lookup orig tuple for IPv6 SNAT nf_sk_lookup_slow_v4 does the conntrack lookup for IPv4 packets to restore the original 5-tuple in case of SNAT, to be able to find the right socket (if any). Then socket_match() can correctly check whether the socket was transparent. However, the IPv6 counterpart (nf_sk_lookup_slow_v6) lacks this conntrack lookup, making xt_socket fail to match on the socket when the packet was SNATed. Add the same logic to nf_sk_lookup_slow_v6. IPv6 SNAT is used in Kubernetes clusters for pod-to-world packets, as pods' addresses are in the fd00::/8 ULA subnet and need to be replaced with the node's external address. Cilium leverages Envoy to enforce L7 policies, and Envoy uses transparent sockets. Cilium inserts an iptables prerouting rule that matches on `-m socket --transparent` and redirects the packets to localhost, but it fails to match SNATed IPv6 packets due to that missing conntrack lookup.

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Changed

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00187.

Key SSVC decision points have not yet been added.

Affected Vendors & Products

Vendors Products
Linux
  • Linux Kernel

Configuration 1 [-]

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:*:*:*:*:*:*:*

No data.

No data.

References
Link Providers
https://git.kernel.org/stable/c/1ca2169cc19dca893c7aae6af122852097435d16 cve-icon cve-icon
https://git.kernel.org/stable/c/1ec43100f7123010730b7ddfc3d5c2eac19e70e7 cve-icon cve-icon
https://git.kernel.org/stable/c/221c27259324ec1404f028d4f5a0f2ae7f63ee23 cve-icon cve-icon
https://git.kernel.org/stable/c/2bb139e483f8cbe488d19d8c1135ac3615e2668c cve-icon cve-icon
https://git.kernel.org/stable/c/41904cbb343d115931d6bf79aa2c815cac4ef72b cve-icon cve-icon
https://git.kernel.org/stable/c/5251041573850e5020cd447374e23010be698898 cve-icon cve-icon
https://git.kernel.org/stable/c/58ab63d3ded2ca6141357a2b24eee8453d0f871d cve-icon cve-icon
https://git.kernel.org/stable/c/6488b96a79a26e19100ad872622f04e93b638d7f cve-icon cve-icon
https://git.kernel.org/stable/c/932b32ffd7604fb00b5c57e239a3cc4d901ccf6e cve-icon cve-icon
https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html cve-icon
https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html cve-icon
https://lore.kernel.org/linux-cve-announce/2025041643-CVE-2025-22021-1089@gregkh/T cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2025-22021 cve-icon
https://www.cve.org/CVERecord?id=CVE-2025-22021 cve-icon
History

Thu, 30 Jul 2026 06:15:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

 cvssV3_1

{'score': 10, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'}

Mon, 03 Nov 2025 20:30:00 +0000

Type Values Removed Values Added
References

Tue, 28 Oct 2025 20:15:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel

Tue, 27 May 2025 03:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-20

Thu, 17 Apr 2025 02:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Wed, 16 Apr 2025 10:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: netfilter: socket: Lookup orig tuple for IPv6 SNAT nf_sk_lookup_slow_v4 does the conntrack lookup for IPv4 packets to restore the original 5-tuple in case of SNAT, to be able to find the right socket (if any). Then socket_match() can correctly check whether the socket was transparent. However, the IPv6 counterpart (nf_sk_lookup_slow_v6) lacks this conntrack lookup, making xt_socket fail to match on the socket when the packet was SNATed. Add the same logic to nf_sk_lookup_slow_v6. IPv6 SNAT is used in Kubernetes clusters for pod-to-world packets, as pods' addresses are in the fd00::/8 ULA subnet and need to be replaced with the node's external address. Cilium leverages Envoy to enforce L7 policies, and Envoy uses transparent sockets. Cilium inserts an iptables prerouting rule that matches on `-m socket --transparent` and redirects the packets to localhost, but it fails to match SNATed IPv6 packets due to that missing conntrack lookup.
Title netfilter: socket: Lookup orig tuple for IPv6 SNAT
References
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-07-30T05:47:37.698Z

Reserved: 2024-12-29T08:45:45.807Z

Link: CVE-2025-22021

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Modified

Published: 2025-04-16T11:15:42.773

Modified: 2026-06-17T08:44:51.833

Link: CVE-2025-22021

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-04-16T00:00:00Z

Links: CVE-2025-22021 - Bugzilla

cve-icon OpenCVE Enrichment

No data.