{"api_version":"1","generated_at":"2026-10-02T11:08:49+00:00","cve":"CVE-2026-90050","urls":{"html":"https://cve.report/CVE-2026-90050","api":"https://cve.report/api/cve/CVE-2026-90050.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-90050","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-90050"},"summary":{"title":"net/sched: fq: clamp quantum and initial_quantum in change path","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq: clamp quantum and initial_quantum in change path\n\nThe fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and\nTCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to\n[1, 1<<20]. A user can override the init clamp via tc qdisc change,\nrestoring the small-quantum deficit spin that the init clamp prevents.\n\nNarrow iq_range.max to 1<<20 so TCA_FQ_INITIAL_QUANTUM is rejected at\nparse time. Clamp TCA_FQ_QUANTUM to [256, 1<<20] in fq_change() and\nfq_init() quantum to [256, 1<<20] for tiny-MTU devices.\n\nConditions to recreate the bug:\n  CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via\n  unshare -Urn suffices).\n\n  tc qdisc add dev dummy0 root fq\n  tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-17 17:16:53","updated_at":"2026-09-17 17:16:53"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/a27498d34c3f429fb6db3aa609569f8154afa175","name":"https://git.kernel.org/stable/c/a27498d34c3f429fb6db3aa609569f8154afa175","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/094cc07f98dfe70a34e2a1923af17fd29b8cf622","name":"https://git.kernel.org/stable/c/094cc07f98dfe70a34e2a1923af17fd29b8cf622","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/72e9387884554f47b03bfd40fb8b2bf52789c68d","name":"https://git.kernel.org/stable/c/72e9387884554f47b03bfd40fb8b2bf52789c68d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/798283cd0fe7ba997f67e5a917f14ab40afa8d9f","name":"https://git.kernel.org/stable/c/798283cd0fe7ba997f67e5a917f14ab40afa8d9f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-90050","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90050","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected d16dac3925be95ad46e986d4b139c9898b6e227f a27498d34c3f429fb6db3aa609569f8154afa175 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f6b3e3848a5fca63438984acd6d9eceac80814c1 798283cd0fe7ba997f67e5a917f14ab40afa8d9f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e35acd56f244d94355f9ab237c2ecc8fba5e6f04 72e9387884554f47b03bfd40fb8b2bf52789c68d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 709f34f7c28dc4dd6c40343d101850f11e172312 094cc07f98dfe70a34e2a1923af17fd29b8cf622 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.3-rc1","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc3 * 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_fq.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"a27498d34c3f429fb6db3aa609569f8154afa175","status":"affected","version":"d16dac3925be95ad46e986d4b139c9898b6e227f","versionType":"git"},{"lessThan":"798283cd0fe7ba997f67e5a917f14ab40afa8d9f","status":"affected","version":"f6b3e3848a5fca63438984acd6d9eceac80814c1","versionType":"git"},{"lessThan":"72e9387884554f47b03bfd40fb8b2bf52789c68d","status":"affected","version":"e35acd56f244d94355f9ab237c2ecc8fba5e6f04","versionType":"git"},{"lessThan":"094cc07f98dfe70a34e2a1923af17fd29b8cf622","status":"affected","version":"709f34f7c28dc4dd6c40343d101850f11e172312","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/sched/sch_fq.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"7.3-rc1"},{"lessThan":"7.3-rc1","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc3","versionStartIncluding":"7.3-rc1","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq: clamp quantum and initial_quantum in change path\n\nThe fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and\nTCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to\n[1, 1<<20]. A user can override the init clamp via tc qdisc change,\nrestoring the small-quantum deficit spin that the init clamp prevents.\n\nNarrow iq_range.max to 1<<20 so TCA_FQ_INITIAL_QUANTUM is rejected at\nparse time. Clamp TCA_FQ_QUANTUM to [256, 1<<20] in fq_change() and\nfq_init() quantum to [256, 1<<20] for tiny-MTU devices.\n\nConditions to recreate the bug:\n  CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via\n  unshare -Urn suffices).\n\n  tc qdisc add dev dummy0 root fq\n  tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0"}],"providerMetadata":{"dateUpdated":"2026-09-17T16:05:36.970Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/a27498d34c3f429fb6db3aa609569f8154afa175"},{"url":"https://git.kernel.org/stable/c/798283cd0fe7ba997f67e5a917f14ab40afa8d9f"},{"url":"https://git.kernel.org/stable/c/72e9387884554f47b03bfd40fb8b2bf52789c68d"},{"url":"https://git.kernel.org/stable/c/094cc07f98dfe70a34e2a1923af17fd29b8cf622"}],"title":"net/sched: fq: clamp quantum and initial_quantum in change path","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-90050","datePublished":"2026-09-17T16:05:36.970Z","dateReserved":"2026-09-11T19:38:34.783Z","dateUpdated":"2026-09-17T16:05:36.970Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-17 17:16:53","lastModifiedDate":"2026-09-17 17:16:53","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"90050","Ordinal":"1","Title":"net/sched: fq: clamp quantum and initial_quantum in change path","CVE":"CVE-2026-90050","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"90050","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq: clamp quantum and initial_quantum in change path\n\nThe fq change path accepts TCA_FQ_QUANTUM in [1, INT_MAX] and\nTCA_FQ_INITIAL_QUANTUM up to INT_MAX, while fq_init() already clamps to\n[1, 1<<20]. A user can override the init clamp via tc qdisc change,\nrestoring the small-quantum deficit spin that the init clamp prevents.\n\nNarrow iq_range.max to 1<<20 so TCA_FQ_INITIAL_QUANTUM is rejected at\nparse time. Clamp TCA_FQ_QUANTUM to [256, 1<<20] in fq_change() and\nfq_init() quantum to [256, 1<<20] for tiny-MTU devices.\n\nConditions to recreate the bug:\n  CONFIG_NET_SCH_FQ=y. Requires CAP_NET_ADMIN (namespace-local via\n  unshare -Urn suffices).\n\n  tc qdisc add dev dummy0 root fq\n  tc qdisc change dev dummy0 root fq quantum 1 stab data 32768 size_log 15 cell_log 0","Type":"Description","Title":"net/sched: fq: clamp quantum and initial_quantum in change path"}]}}}