{"cve":"CVE-2025-22021","nvd":{"published":"2025-04-16T11:15:42.773","modified":"2026-10-15T22:18:13.463","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: socket: Lookup orig tuple for IPv6 SNAT\n\nnf_sk_lookup_slow_v4 does the conntrack lookup for IPv4 packets to\nrestore the original 5-tuple in case of SNAT, to be able to find the\nright socket (if any). Then socket_match() can correctly check whether\nthe socket was transparent.\n\nHowever, the IPv6 counterpart (nf_sk_lookup_slow_v6) lacks this\nconntrack lookup, making xt_socket fail to match on the socket when the\npacket was SNATed. Add the same logic to nf_sk_lookup_slow_v6.\n\nIPv6 SNAT is used in Kubernetes clusters for pod-to-world packets, as\npods' addresses are in the fd00::/8 ULA subnet and need to be replaced\nwith the node's external address. Cilium leverages Envoy to enforce L7\npolicies, and Envoy uses transparent sockets. Cilium inserts an iptables\nprerouting rule that matches on `-m socket --transparent` and redirects\nthe packets to localhost, but it fails to match SNATed IPv6 packets due\nto that missing conntrack lookup.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/1ca2169cc19dca893c7aae6af122852097435d16","https://git.kernel.org/stable/c/1ec43100f7123010730b7ddfc3d5c2eac19e70e7","https://git.kernel.org/stable/c/221c27259324ec1404f028d4f5a0f2ae7f63ee23","https://git.kernel.org/stable/c/2bb139e483f8cbe488d19d8c1135ac3615e2668c","https://git.kernel.org/stable/c/41904cbb343d115931d6bf79aa2c815cac4ef72b"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:01:11.054312287+00:00"},"epss":{"cve":"CVE-2025-22021","score":0.00471,"percentile":0.40451,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}