CVE-2025-22021

netfilter: socket: Lookup orig tuple for IPv6 SNAT

State: Published
Severity: 10.0 Critical
Published: Apr 16, 2025
Updated: Oct 15, 2026
Reserved: Dec 29, 2024

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.

Scores

CVSS	Score	Vector	Source
3.1	10.0 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 6488b96a79a26e19100ad872622f04e93b638d7fAffected eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 58ab63d3ded2ca6141357a2b24eee8453d0f871dAffected eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 1ca2169cc19dca893c7aae6af122852097435d16Affected eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 1ec43100f7123010730b7ddfc3d5c2eac19e70e7Affected eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 5251041573850e5020cd447374e23010be698898Affected eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 2bb139e483f8cbe488d19d8c1135ac3615e2668cAffected eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 41904cbb343d115931d6bf79aa2c815cac4ef72bAffected eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 221c27259324ec1404f028d4f5a0f2ae7f63ee23Affected eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 932b32ffd7604fb00b5c57e239a3cc4d901ccf6eAffected
LinuxLinux	3.13Affected before 3.13Not affected 5.4.292 through 5.4.Not affected 5.10.236 through 5.10.Not affected 5.15.180 through 5.15.Not affected 6.1.133 through 6.1.Not affected 6.6.86 through 6.6.Not affected 6.12.22 through 6.12.Not affected 6.13.10 through 6.13.Not affected 6.14.1 through 6.14.Not affected 6.15 and laterNot affected

Product

Versions

LinuxLinux

eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 6488b96a79a26e19100ad872622f04e93b638d7fAffected
eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 58ab63d3ded2ca6141357a2b24eee8453d0f871dAffected
eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 1ca2169cc19dca893c7aae6af122852097435d16Affected
eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 1ec43100f7123010730b7ddfc3d5c2eac19e70e7Affected
eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 5251041573850e5020cd447374e23010be698898Affected
eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 2bb139e483f8cbe488d19d8c1135ac3615e2668cAffected
eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 41904cbb343d115931d6bf79aa2c815cac4ef72bAffected
eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 221c27259324ec1404f028d4f5a0f2ae7f63ee23Affected
eb31628e37a0a4e01fffd79dcc7f815d2357f53a to before 932b32ffd7604fb00b5c57e239a3cc4d901ccf6eAffected

LinuxLinux

3.13Affected
before 3.13Not affected
5.4.292 through 5.4.*Not affected
5.10.236 through 5.10.*Not affected
5.15.180 through 5.15.*Not affected
6.1.133 through 6.1.*Not affected
6.6.86 through 6.6.*Not affected
6.12.22 through 6.12.*Not affected
6.13.10 through 6.13.*Not affected
6.14.1 through 6.14.*Not affected
6.15 and laterNot affected

References

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