{"id":"CVE-2025-38472","revision":null,"records":[{"revision":"75d5df721228449ab8f8e4d8f78dc6ac","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-38472","aliases":[],"title":"netfilter: nf_conntrack: fix crash due to removal of uninitialised entry","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack: fix crash due to removal of uninitialised entry\n\nA crash in conntrack was reported while trying to unlink the conntrack\nentry from the hash bucket list:\n    [exception RIP: __nf_ct_delete_from_lists+172]\n    [..]\n #7 [ff539b5a2b043aa0] nf_ct_delete at ffffffffc124d421 [nf_conntrack]\n #8 [ff539b5a2b043ad0] nf_ct_gc_expired at ffffffffc124d999 [nf_conntrack]\n #9 [ff539b5a2b043ae0] __nf_conntrack_find_get at ffffffffc124efbc [nf_conntrack]\n    [..]\n\nThe nf_conn struct is marked as allocated from slab but appears to be in\na partially initialised state:\n\n ct hlist pointer is garbage; looks like the ct hash value\n (hence crash).\n ct->status is equal to IPS_CONFIRMED|IPS_DYING, which is expected\n ct->timeout is 30000 (=30s), which is unexpected.\n\nEverything else looks like normal udp conntrack entry.  If we ignore\nct->status and pretend its 0, the entry matches those that are newly\nallocated but not yet inserted into the hash:\n  - ct hlist pointers are overloaded and store/cache the raw tuple hash\n  - ct->timeout matches the relative time expected for a new udp flow\n    rather than the absolute 'jiffies' value.\n\nIf it were not for the presence of IPS_CONFIRMED,\n__nf_conntrack_find_get() would have skipped the entry.\n\nTheory is that we did hit following race:\n\ncpu x \t\t\tcpu y\t\t\tcpu z\n found entry E\t\tfound entry E\n E is expired\t\t<preemption>\n nf_ct_delete()\n return E to rcu slab\n\t\t\t\t\tinit_conntrack\n\t\t\t\t\tE is re-inited,\n\t\t\t\t\tct->status set to 0\n\t\t\t\t\treply tuplehash hnnode.pprev\n\t\t\t\t\tstores hash value.\n\ncpu y found E right before it was deleted on cpu x.\nE is now re-inited on cpu z.  cpu y was preempted before\nchecking for expiry and/or confirm bit.\n\n\t\t\t\t\t->refcnt set to 1\n\t\t\t\t\tE now owned by skb\n\t\t\t\t\t->timeout set to 30000\n\nIf cpu y were to resume now, it would observe E as\nexpired but would skip E due to missing CONFIRMED bit.\n\n\t\t\t\t\tnf_conntrack_confirm gets called\n\t\t\t\t\tsets: ct->status |= CONFIRMED\n\t\t\t\t\tThis is wrong: E is not yet added\n\t\t\t\t\tto hashtable.\n\ncpu y resumes, it observes E as expired but CONFIRMED:\n\t\t\t<resumes>\n\t\t\tnf_ct_expired()\n\t\t\t -> yes (ct->timeout is 30s)\n\t\t\tconfirmed bit set.\n\ncpu y will try to delete E from the hashtable:\n\t\t\tnf_ct_delete() -> set DYING bit\n\t\t\t__nf_ct_delete_from_lists\n\nEven this scenario doesn't guarantee a crash:\ncpu z still holds the table bucket lock(s) so y blocks:\n\n\t\t\twait for spinlock held by z\n\n\t\t\t\t\tCONFIRMED is set but there is no\n\t\t\t\t\tguarantee ct will be added to hash:\n\t\t\t\t\t\"chaintoolong\" or \"clash resolution\"\n\t\t\t\t\tlogic both skip the insert step.\n\t\t\t\t\treply hnnode.pprev still stores the\n\t\t\t\t\thash value.\n\n\t\t\t\t\tunlocks spinlock\n\t\t\t\t\treturn NF_DROP\n\t\t\t<unblocks, then\n\t\t\t crashes on hlist_nulls_del_rcu pprev>\n\nIn case CPU z does insert the entry into the hashtable, cpu y will unlink\nE again right away but no crash occurs.\n\nWithout 'cpu y' race, 'garbage' hlist is of no consequence:\nct refcnt remains at 1, eventually skb will be free'd and E gets\ndestroyed via: nf_conntrack_put -> nf_conntrack_destroy -> nf_ct_destroy.\n\nTo resolve this, move the IPS_CONFIRMED assignment after the table\ninsertion but before the unlock.\n\nPablo points out that the confirm-bit-store could be reordered to happen\nbefore hlist add resp. the timeout fixup, so switch to set_bit and\nbefore_atomic memory barrier to prevent this.\n\nIt doesn't matter if other CPUs can observe a newly inserted entry right\nbefore the CONFIRMED bit was set:\n\nSuch event cannot be distinguished from above \"E is the old incarnation\"\ncase: the entry will be skipped.\n\nAlso change nf_ct_should_gc() to first check the confirmed bit.\n\nThe gc sequence is:\n 1. Check if entry has expired, if not skip to next entry\n 2. Obtain a reference to the expired entry.\n 3. Call nf_ct_should_gc() to double-check step 1.\n\nnf_ct_should_gc() is thus called only for entries that already failed an\nexpiry check. After this patch, once the confirmed bit check pas\n---truncated---","state":0,"publishedAt":"2025-07-28T11:21:33.977+00:00","modifiedAt":"2026-10-15T21:52:17.084+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/netfilter/nf_conntrack.h\",\n                        \"net/netfilter/nf_conntrack_core.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"1397af5bfd7d32b0cf2adb70a78c9a9e8f11d912\",\n                            \"lessThan\": \"a47ef874189d47f934d0809ae738886307c0ea22\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1397af5bfd7d32b0cf2adb70a78c9a9e8f11d912\",\n                            \"lessThan\": \"76179961c423cd698080b5e4d5583cf7f4fcdde9\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1397af5bfd7d32b0cf2adb70a78c9a9e8f11d912\",\n                            \"lessThan\": \"fc38c249c622ff5e3011b8845fd49dbfd9289afc\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1397af5bfd7d32b0cf2adb70a78c9a9e8f11d912\",\n                            \"lessThan\": \"938ce0e8422d3793fe30df2ed0e37f6bc0598379\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1397af5bfd7d32b0cf2adb70a78c9a9e8f11d912\",\n                            \"lessThan\": \"2d72afb340657f03f7261e9243b44457a9228ac7\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"594cea2c09f7cd440d1ee1c4547d5bc6a646b0e4\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"5.18.13\",\n                            \"lessThan\": \"5.19\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\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/netfilter/nf_conntrack.h\",\n                        \"net/netfilter/nf_conntrack_core.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\": \"6.1.147\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.100\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.40\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.15.8\",\n                            \"lessThanOrEqual\": \"6.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.16\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/a47ef874189d47f934d0809ae738886307c0ea22","https://git.kernel.org/stable/c/76179961c423cd698080b5e4d5583cf7f4fcdde9","https://git.kernel.org/stable/c/fc38c249c622ff5e3011b8845fd49dbfd9289afc","https://git.kernel.org/stable/c/938ce0e8422d3793fe30df2ed0e37f6bc0598379","https://git.kernel.org/stable/c/2d72afb340657f03f7261e9243b44457a9228ac7"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-38472","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-38472","identifiers":["CVE-2025-38472"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-11-09T12:02:21.9910047+00:00","complete":true,"records":1769,"lastAttemptAt":"2026-11-09T12:02:21.9910047+00:00","lastSuccessAt":"2026-11-09T12:02:22.1773794+00:00","error":null,"lastVerifiedAt":"2026-11-09T12:02:22.1773831+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-24e6fde7b744113daefb8f6135035fb8a5c69c9617c9c0d40574a0376532ffd3-bc5670b92e6417137e6d98178f734a585c0efdac3c24cdab996a156ba398735b","complete":true,"records":421397,"lastAttemptAt":"2026-11-09T12:02:16.4943065+00:00","lastSuccessAt":"2026-11-09T12:02:16.4102763+00:00","error":null,"lastVerifiedAt":"2026-11-09T12:02:16.4943065+00:00","snapshotPublishedAt":"2026-11-09T11:21:04+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-469e0902b40147e98a6498cf72d41be8","complete":true,"records":13655,"lastAttemptAt":"2026-11-09T12:14:17.3321495+00:00","lastSuccessAt":"2026-11-09T12:14:17.327+00:00","error":null,"lastVerifiedAt":"2026-11-09T12:14:17.327+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13707,"expectedIdentifiers":13707,"failedIdentifiers":0},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-11-09T12:02:21.9910047+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-09T12:02:21.9910047+00:00","lastSuccessAt":"2026-11-09T12:02:22.1781502+00:00","error":null,"lastVerifiedAt":"2026-11-09T12:02:22.1781508+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. No reader inventory is sent.","generation":"enrichment-44231a3c29e84c64b271bb4e9b8f3678","complete":true,"records":13667,"lastAttemptAt":"2026-11-09T12:02:23.2886601+00:00","lastSuccessAt":"2026-11-09T12:02:23.284+00:00","error":null,"lastVerifiedAt":"2026-11-09T12:02:23.284+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13707,"expectedIdentifiers":13707,"failedIdentifiers":0},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-980593e6977a6d1b4fb1eed5a1ffe88a468736f89f0a06f710924ad59132c023","complete":true,"records":9914,"lastAttemptAt":"2026-11-09T12:02:17.2599038+00:00","lastSuccessAt":"2026-11-08T11:07:07.068788+00:00","error":null,"lastVerifiedAt":"2026-11-09T12:02:17.2599038+00:00","snapshotPublishedAt":"2026-11-08T11:02:46+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-fde804134ecdda0ddd5ff5c26ee1fff5a6fa659311f7ef2e51c6ad54964db0e2","complete":true,"records":1971,"lastAttemptAt":"2026-11-09T12:02:16.7165115+00:00","lastSuccessAt":"2026-11-06T19:03:17.0399903+00:00","error":null,"lastVerifiedAt":"2026-11-09T12:02:16.7165115+00:00","snapshotPublishedAt":"2026-11-06T18:17:57+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-c905fa1bd26c7b261e77cc7202a86dc766ff31c2b096b501f3bf44f561e34970","complete":true,"records":3063,"lastAttemptAt":"2026-11-09T12:02:21.9559708+00:00","lastSuccessAt":"2026-11-09T12:02:21.7931207+00:00","error":null,"lastVerifiedAt":"2026-11-09T12:02:21.9559708+00:00","snapshotPublishedAt":"2026-11-09T11:18:00+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-e6e6ac3eaece246ff08884368fe1dc99d4d393571e77c126c8f4d38d66697688","complete":true,"records":231297,"lastAttemptAt":"2026-11-09T12:02:17.0901763+00:00","lastSuccessAt":"2026-11-09T10:04:27.0059369+00:00","error":null,"lastVerifiedAt":"2026-11-09T12:02:17.0901763+00:00","snapshotPublishedAt":"2026-11-09T09:33:10+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}