{"id":"CVE-2025-21864","revision":null,"records":[{"revision":"216076125f424c51a34dea73c9072482","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-21864","aliases":[],"title":"tcp: drop secpath at the same time as we currently drop dst","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: drop secpath at the same time as we currently drop dst\n\nXiumei reported hitting the WARN in xfrm6_tunnel_net_exit while\nrunning tests that boil down to:\n - create a pair of netns\n - run a basic TCP test over ipcomp6\n - delete the pair of netns\n\nThe xfrm_state found on spi_byaddr was not deleted at the time we\ndelete the netns, because we still have a reference on it. This\nlingering reference comes from a secpath (which holds a ref on the\nxfrm_state), which is still attached to an skb. This skb is not\nleaked, it ends up on sk_receive_queue and then gets defer-free'd by\nskb_attempt_defer_free.\n\nThe problem happens when we defer freeing an skb (push it on one CPU's\ndefer_list), and don't flush that list before the netns is deleted. In\nthat case, we still have a reference on the xfrm_state that we don't\nexpect at this point.\n\nWe already drop the skb's dst in the TCP receive path when it's no\nlonger needed, so let's also drop the secpath. At this point,\ntcp_filter has already called into the LSM hooks that may require the\nsecpath, so it should not be needed anymore. However, in some of those\nplaces, the MPTCP extension has just been attached to the skb, so we\ncannot simply drop all extensions.","state":0,"publishedAt":"2025-03-12T09:42:21.223+00:00","modifiedAt":"2026-10-15T01:04:56.434+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"include/net/tcp.h\",\n                        \"net/ipv4/tcp_fastopen.c\",\n                        \"net/ipv4/tcp_input.c\",\n                        \"net/ipv4/tcp_ipv4.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"68822bdf76f10c3dc80609d4e2cdc1e847429086\",\n                            \"lessThan\": \"87858bbf21da239ace300d61dd209907995c0491\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"68822bdf76f10c3dc80609d4e2cdc1e847429086\",\n                            \"lessThan\": \"f1d5e6a5e468308af7759cf5276779d3155c5e98\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"68822bdf76f10c3dc80609d4e2cdc1e847429086\",\n                            \"lessThan\": \"cd34a07f744451e2ecf9005bb7d24d0b2fb83656\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"68822bdf76f10c3dc80609d4e2cdc1e847429086\",\n                            \"lessThan\": \"69cafd9413084cd5012cf5d7c7ec6f3d493726d9\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"68822bdf76f10c3dc80609d4e2cdc1e847429086\",\n                            \"lessThan\": \"9b6412e6979f6f9e0632075f8f008937b5cd4efd\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"include/net/tcp.h\",\n                        \"net/ipv4/tcp_fastopen.c\",\n                        \"net/ipv4/tcp_input.c\",\n                        \"net/ipv4/tcp_ipv4.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"5.19\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"5.19\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.130\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.80\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.17\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.13.5\",\n                            \"lessThanOrEqual\": \"6.13.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.14\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/87858bbf21da239ace300d61dd209907995c0491","https://git.kernel.org/stable/c/f1d5e6a5e468308af7759cf5276779d3155c5e98","https://git.kernel.org/stable/c/cd34a07f744451e2ecf9005bb7d24d0b2fb83656","https://git.kernel.org/stable/c/69cafd9413084cd5012cf5d7c7ec6f3d493726d9","https://git.kernel.org/stable/c/9b6412e6979f6f9e0632075f8f008937b5cd4efd"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-21864","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-21864","identifiers":["CVE-2025-21864"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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Not a global EPSS backfill.","generation":"2026-11-09T19:02:11.0282238+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-09T19:02:11.0282238+00:00","lastSuccessAt":"2026-11-09T19:02:11.2551731+00:00","error":null,"lastVerifiedAt":"2026-11-09T19:02:11.2551735+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. 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