{"id":"CVE-2025-21971","revision":null,"records":[{"revision":"7a58d13452804a47b2cc89ed25dcd24b","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-21971","aliases":[],"title":"net_sched: Prevent creation of classes with TC_H_ROOT","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: Prevent creation of classes with TC_H_ROOT\n\nThe function qdisc_tree_reduce_backlog() uses TC_H_ROOT as a termination\ncondition when traversing up the qdisc tree to update parent backlog\ncounters. However, if a class is created with classid TC_H_ROOT, the\ntraversal terminates prematurely at this class instead of reaching the\nactual root qdisc, causing parent statistics to be incorrectly maintained.\nIn case of DRR, this could lead to a crash as reported by Mingi Cho.\n\nPrevent the creation of any Qdisc class with classid TC_H_ROOT\n(0xFFFFFFFF) across all qdisc types, as suggested by Jamal.","state":0,"publishedAt":"2025-04-01T15:47:04.448+00:00","modifiedAt":"2026-10-15T21:51:56.131+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 \"net/sched/sch_api.c\"\n ],\n \"versions\": [\n {\n \"version\": \"066a3b5b2346febf9a655b444567b7138e3bb939\",\n \"lessThan\": \"e05d9938b1b0ac40b6054cc5fa0ccbd9afd5ed4c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"066a3b5b2346febf9a655b444567b7138e3bb939\",\n \"lessThan\": \"7a82fe67a9f4d7123d8e5ba8f0f0806c28695006\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"066a3b5b2346febf9a655b444567b7138e3bb939\",\n \"lessThan\": \"003d92c91cdb5a64b25a9a74cb8543aac9a8bb48\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"066a3b5b2346febf9a655b444567b7138e3bb939\",\n \"lessThan\": \"e5ee00607bbfc97ef1526ea95b6b2458ac9e7cb7\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"066a3b5b2346febf9a655b444567b7138e3bb939\",\n \"lessThan\": \"78533c4a29ac3aeddce4b481770beaaa4f3bfb67\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"066a3b5b2346febf9a655b444567b7138e3bb939\",\n \"lessThan\": \"5c3ca9cb48b51bd72bf76b8b05e24f3cd53db5e7\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"066a3b5b2346febf9a655b444567b7138e3bb939\",\n \"lessThan\": \"94edfdfb9505ab608e86599d1d1e38c83816fc1c\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"066a3b5b2346febf9a655b444567b7138e3bb939\",\n \"lessThan\": \"0c3057a5a04d07120b3d0ec9c79568fceb9c921e\",\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 \"net/sched/sch_api.c\"\n ],\n \"versions\": [\n {\n \"version\": \"2.6.25\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"2.6.25\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.4.292\",\n \"lessThanOrEqual\": \"5.4.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.10.236\",\n \"lessThanOrEqual\": \"5.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.180\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.132\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.84\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.20\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.13.8\",\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/e05d9938b1b0ac40b6054cc5fa0ccbd9afd5ed4c","https://git.kernel.org/stable/c/7a82fe67a9f4d7123d8e5ba8f0f0806c28695006","https://git.kernel.org/stable/c/003d92c91cdb5a64b25a9a74cb8543aac9a8bb48","https://git.kernel.org/stable/c/e5ee00607bbfc97ef1526ea95b6b2458ac9e7cb7","https://git.kernel.org/stable/c/78533c4a29ac3aeddce4b481770beaaa4f3bfb67","https://git.kernel.org/stable/c/5c3ca9cb48b51bd72bf76b8b05e24f3cd53db5e7","https://git.kernel.org/stable/c/94edfdfb9505ab608e86599d1d1e38c83816fc1c","https://git.kernel.org/stable/c/0c3057a5a04d07120b3d0ec9c79568fceb9c921e"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-21971","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-21971","identifiers":["CVE-2025-21971"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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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-897f1f8852214f7d97a85b009edb7d92","complete":false,"records":13655,"lastAttemptAt":"2026-11-09T13:16:47.5163098+00:00","lastSuccessAt":"2026-11-09T13:16:47.505+00:00","error":"7 identifier lookups failed; latest failures include HTTP 403. Other identifiers were checked independently.","lastVerifiedAt":"2026-11-09T13:16:47.505+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13700,"expectedIdentifiers":13707,"failedIdentifiers":7},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. 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