{"api_version":"1","generated_at":"2026-08-15T15:07:55+00:00","cve":"CVE-2026-74284","urls":{"html":"https://cve.report/CVE-2026-74284","api":"https://cve.report/api/cve/CVE-2026-74284.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-74284","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74284"},"summary":{"title":"net/sched: sch_hfsc: Don't make class passive twice","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_hfsc: Don't make class passive twice\n\nupdate_vf() is called from two places for the same class during a single\ndequeue when the class's child qdisc (e.g. codel/fq_codel) drops its last\npackets while dequeuing:\n\n1. The child calls qdisc_tree_reduce_backlog(), which, now that the child\n   is empty, invokes hfsc_qlen_notify() -> update_vf(cl, 0, 0) and turns\n   the class passive (cl_nactive is decremented up the hierarchy).\n\n2. hfsc_dequeue() then calls update_vf(cl, qdisc_pkt_len(skb), cur_time)\n   to charge the dequeued bytes.\n\nOn the second call the class is already passive, but its child qdisc is\nstill empty, so update_vf() arms go_passive again:\n\n      if (cl->qdisc->q.qlen == 0 && cl->cl_flags & HFSC_FSC)\n              go_passive = 1;\n\nThe leaf is then skipped by the cl_nactive == 0 check inside the loop,\nwhich does not clear go_passive, so the stale go_passive propagates to the\nparent and decrements its cl_nactive a second time. A parent that still\nhas other active children is driven to cl_nactive == 0 and removed from\nthe vttree, even though those siblings are still backlogged. They are\nnever dequeued again and the qdisc stalls.\n\nFix this by only arming go_passive when the class is actually active, so an\nalready-passive class no longer triggers a second passive transition. The\nbyte accounting (cl->cl_total += len) still runs for every ancestor, so\ndequeued bytes continue to be counted exactly once.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:22:27","updated_at":"2026-08-15 06:22:27"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/fc973ecd1a079b9a87c360478542f3a56dea085b","name":"https://git.kernel.org/stable/c/fc973ecd1a079b9a87c360478542f3a56dea085b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b2a017bfcf565721918ec7355a373911d2f2a227","name":"https://git.kernel.org/stable/c/b2a017bfcf565721918ec7355a373911d2f2a227","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/90b662ea25f5e83bb3b8ccec5b93ced810b92fb8","name":"https://git.kernel.org/stable/c/90b662ea25f5e83bb3b8ccec5b93ced810b92fb8","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/15720cd8fa3fc625146128f89a8e11b0449a20a7","name":"https://git.kernel.org/stable/c/15720cd8fa3fc625146128f89a8e11b0449a20a7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a425c82ff06cda5165e0de3de8c2a445ec1f863e","name":"https://git.kernel.org/stable/c/a425c82ff06cda5165e0de3de8c2a445ec1f863e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9221a594c72a1446137926d4c2aa04e345f798dc","name":"https://git.kernel.org/stable/c/9221a594c72a1446137926d4c2aa04e345f798dc","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/66dbb13eeb2fc339f8f548a9076be4c1a94857b0","name":"https://git.kernel.org/stable/c/66dbb13eeb2fc339f8f548a9076be4c1a94857b0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3a49bbae676fef1ffe548971e6229ae2adeb9d10","name":"https://git.kernel.org/stable/c/3a49bbae676fef1ffe548971e6229ae2adeb9d10","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-74284","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74284","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 72c61ffbeeb8c50f6d4d70c65d3283aa1bac57a7 a425c82ff06cda5165e0de3de8c2a445ec1f863e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a5efc95a33bd4fcb879250852828cc58c7862970 fc973ecd1a079b9a87c360478542f3a56dea085b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0475c85426b18eccdcb7f9fb58d8f8e9c6c58c87 15720cd8fa3fc625146128f89a8e11b0449a20a7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9030a91235ae4845ec71902c3e0cecfc9ed1f2df b2a017bfcf565721918ec7355a373911d2f2a227 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d06476714d2819b550e0cc39222347e2c8941c9d 9221a594c72a1446137926d4c2aa04e345f798dc git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 51eb3b65544c9efd6a1026889ee5fb5aa62da3bb 66dbb13eeb2fc339f8f548a9076be4c1a94857b0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 51eb3b65544c9efd6a1026889ee5fb5aa62da3bb 3a49bbae676fef1ffe548971e6229ae2adeb9d10 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 51eb3b65544c9efd6a1026889ee5fb5aa62da3bb 90b662ea25f5e83bb3b8ccec5b93ced810b92fb8 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 9a5fd5c2f4d4afdd5e405083ee53e0789ce76956 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c1175c4ad01dbc9c979d099861fa90a754f72059 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.10.241 5.10.261 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.15.190 5.15.212 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.1.138 6.1.178 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6.90 6.6.145 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12.28 6.12.97 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.4.297 5.5 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.14.6 6.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.15","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.261 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.212 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.178 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.145 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.97 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.40 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.5 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/sched/sch_hfsc.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"a425c82ff06cda5165e0de3de8c2a445ec1f863e","status":"affected","version":"72c61ffbeeb8c50f6d4d70c65d3283aa1bac57a7","versionType":"git"},{"lessThan":"fc973ecd1a079b9a87c360478542f3a56dea085b","status":"affected","version":"a5efc95a33bd4fcb879250852828cc58c7862970","versionType":"git"},{"lessThan":"15720cd8fa3fc625146128f89a8e11b0449a20a7","status":"affected","version":"0475c85426b18eccdcb7f9fb58d8f8e9c6c58c87","versionType":"git"},{"lessThan":"b2a017bfcf565721918ec7355a373911d2f2a227","status":"affected","version":"9030a91235ae4845ec71902c3e0cecfc9ed1f2df","versionType":"git"},{"lessThan":"9221a594c72a1446137926d4c2aa04e345f798dc","status":"affected","version":"d06476714d2819b550e0cc39222347e2c8941c9d","versionType":"git"},{"lessThan":"66dbb13eeb2fc339f8f548a9076be4c1a94857b0","status":"affected","version":"51eb3b65544c9efd6a1026889ee5fb5aa62da3bb","versionType":"git"},{"lessThan":"3a49bbae676fef1ffe548971e6229ae2adeb9d10","status":"affected","version":"51eb3b65544c9efd6a1026889ee5fb5aa62da3bb","versionType":"git"},{"lessThan":"90b662ea25f5e83bb3b8ccec5b93ced810b92fb8","status":"affected","version":"51eb3b65544c9efd6a1026889ee5fb5aa62da3bb","versionType":"git"},{"status":"affected","version":"9a5fd5c2f4d4afdd5e405083ee53e0789ce76956","versionType":"git"},{"status":"affected","version":"c1175c4ad01dbc9c979d099861fa90a754f72059","versionType":"git"},{"lessThan":"5.10.261","status":"affected","version":"5.10.241","versionType":"semver"},{"lessThan":"5.15.212","status":"affected","version":"5.15.190","versionType":"semver"},{"lessThan":"6.1.178","status":"affected","version":"6.1.138","versionType":"semver"},{"lessThan":"6.6.145","status":"affected","version":"6.6.90","versionType":"semver"},{"lessThan":"6.12.97","status":"affected","version":"6.12.28","versionType":"semver"},{"lessThan":"5.5","status":"affected","version":"5.4.297","versionType":"semver"},{"lessThan":"6.15","status":"affected","version":"6.14.6","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/sched/sch_hfsc.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.15"},{"lessThan":"6.15","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.261","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.212","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.178","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.145","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.97","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.40","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.5","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.261","versionStartIncluding":"5.10.241","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.212","versionStartIncluding":"5.15.190","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.178","versionStartIncluding":"6.1.138","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.145","versionStartIncluding":"6.6.90","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.97","versionStartIncluding":"6.12.28","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.40","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.5","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2-rc1","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4.297","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14.6","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_hfsc: Don't make class passive twice\n\nupdate_vf() is called from two places for the same class during a single\ndequeue when the class's child qdisc (e.g. codel/fq_codel) drops its last\npackets while dequeuing:\n\n1. The child calls qdisc_tree_reduce_backlog(), which, now that the child\n   is empty, invokes hfsc_qlen_notify() -> update_vf(cl, 0, 0) and turns\n   the class passive (cl_nactive is decremented up the hierarchy).\n\n2. hfsc_dequeue() then calls update_vf(cl, qdisc_pkt_len(skb), cur_time)\n   to charge the dequeued bytes.\n\nOn the second call the class is already passive, but its child qdisc is\nstill empty, so update_vf() arms go_passive again:\n\n      if (cl->qdisc->q.qlen == 0 && cl->cl_flags & HFSC_FSC)\n              go_passive = 1;\n\nThe leaf is then skipped by the cl_nactive == 0 check inside the loop,\nwhich does not clear go_passive, so the stale go_passive propagates to the\nparent and decrements its cl_nactive a second time. A parent that still\nhas other active children is driven to cl_nactive == 0 and removed from\nthe vttree, even though those siblings are still backlogged. They are\nnever dequeued again and the qdisc stalls.\n\nFix this by only arming go_passive when the class is actually active, so an\nalready-passive class no longer triggers a second passive transition. The\nbyte accounting (cl->cl_total += len) still runs for every ancestor, so\ndequeued bytes continue to be counted exactly once."}],"providerMetadata":{"dateUpdated":"2026-08-15T05:57:53.290Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a425c82ff06cda5165e0de3de8c2a445ec1f863e"},{"url":"https://git.kernel.org/stable/c/fc973ecd1a079b9a87c360478542f3a56dea085b"},{"url":"https://git.kernel.org/stable/c/15720cd8fa3fc625146128f89a8e11b0449a20a7"},{"url":"https://git.kernel.org/stable/c/b2a017bfcf565721918ec7355a373911d2f2a227"},{"url":"https://git.kernel.org/stable/c/9221a594c72a1446137926d4c2aa04e345f798dc"},{"url":"https://git.kernel.org/stable/c/66dbb13eeb2fc339f8f548a9076be4c1a94857b0"},{"url":"https://git.kernel.org/stable/c/3a49bbae676fef1ffe548971e6229ae2adeb9d10"},{"url":"https://git.kernel.org/stable/c/90b662ea25f5e83bb3b8ccec5b93ced810b92fb8"}],"title":"net/sched: sch_hfsc: Don't make class passive twice","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-74284","datePublished":"2026-08-15T05:57:53.290Z","dateReserved":"2026-08-15T05:44:03.881Z","dateUpdated":"2026-08-15T05:57:53.290Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:22:27","lastModifiedDate":"2026-08-15 06:22:27","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"74284","Ordinal":"1","Title":"net/sched: sch_hfsc: Don't make class passive twice","CVE":"CVE-2026-74284","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"74284","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_hfsc: Don't make class passive twice\n\nupdate_vf() is called from two places for the same class during a single\ndequeue when the class's child qdisc (e.g. codel/fq_codel) drops its last\npackets while dequeuing:\n\n1. The child calls qdisc_tree_reduce_backlog(), which, now that the child\n   is empty, invokes hfsc_qlen_notify() -> update_vf(cl, 0, 0) and turns\n   the class passive (cl_nactive is decremented up the hierarchy).\n\n2. hfsc_dequeue() then calls update_vf(cl, qdisc_pkt_len(skb), cur_time)\n   to charge the dequeued bytes.\n\nOn the second call the class is already passive, but its child qdisc is\nstill empty, so update_vf() arms go_passive again:\n\n      if (cl->qdisc->q.qlen == 0 && cl->cl_flags & HFSC_FSC)\n              go_passive = 1;\n\nThe leaf is then skipped by the cl_nactive == 0 check inside the loop,\nwhich does not clear go_passive, so the stale go_passive propagates to the\nparent and decrements its cl_nactive a second time. A parent that still\nhas other active children is driven to cl_nactive == 0 and removed from\nthe vttree, even though those siblings are still backlogged. They are\nnever dequeued again and the qdisc stalls.\n\nFix this by only arming go_passive when the class is actually active, so an\nalready-passive class no longer triggers a second passive transition. The\nbyte accounting (cl->cl_total += len) still runs for every ancestor, so\ndequeued bytes continue to be counted exactly once.","Type":"Description","Title":"net/sched: sch_hfsc: Don't make class passive twice"}]}}}