{"api_version":"1","generated_at":"2026-09-20T02:46:08+00:00","cve":"CVE-2026-90075","urls":{"html":"https://cve.report/CVE-2026-90075","api":"https://cve.report/api/cve/CVE-2026-90075.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-90075","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-90075"},"summary":{"title":"net/sched: fq_codel: clamp default quantum and mtu","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq_codel: clamp default quantum and mtu\n\nfq_codel_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) without\nclamping. A device with a huge MTU (e.g. dummy with max_mtu == 0\naccepting MTU 2147483634) makes psched_mtu() return 0x80000000, which\noverflows the signed flow->deficit to INT_MIN in fq_codel_dequeue(),\ncausing an infinite loop and soft lockup. Emulate fq_codel_change()\nand constrain to [256, FQ_CODEL_QUANTUM_MAX].\n\nThe same unclamped psched_mtu() is assigned to q->cparams.mtu a bit\nbelow, and fq_codel_change() never updates it. codel_should_drop()\ntests \"*backlog <= params->mtu\"; with mtu == 0x80000000 (~2 GiB) and\nthe default 32 MiB memory_limit, the test is always true, so CoDel is\nsilently and completely disabled (no drops, no ECN). Declare a single\nclamped mtu and assign both q->quantum and q->cparams.mtu from it,\nwhich also removes the double psched_mtu() call.\n\nConditions to recreate the bug: a device whose MTU (plus\nhard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy\ndevice with max_mtu == 0 accepting MTU 2147483634). Requires\nCAP_NET_ADMIN in a user namespace.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-17 17:16:56","updated_at":"2026-09-17 17:16:56"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/397e2b1f71d9f15b8b4e47d24eb620e4dff8878d","name":"https://git.kernel.org/stable/c/397e2b1f71d9f15b8b4e47d24eb620e4dff8878d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9f499e5827fdb6d7fdb46a7ce731852f6b1a1bb9","name":"https://git.kernel.org/stable/c/9f499e5827fdb6d7fdb46a7ce731852f6b1a1bb9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/324f86806673ae4a55f66d28db84577f46f615e1","name":"https://git.kernel.org/stable/c/324f86806673ae4a55f66d28db84577f46f615e1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a9a5b2943a00df2ab81a2209f31dd9e87016f120","name":"https://git.kernel.org/stable/c/a9a5b2943a00df2ab81a2209f31dd9e87016f120","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/dfb4b61db886917244284b18b44b23d2254b82c2","name":"https://git.kernel.org/stable/c/dfb4b61db886917244284b18b44b23d2254b82c2","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3782067ec0d485628b6f1f9ede3eeeb4f611fcf2","name":"https://git.kernel.org/stable/c/3782067ec0d485628b6f1f9ede3eeeb4f611fcf2","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d315ee8a07fd1810880227319cf60e6cd925ef22","name":"https://git.kernel.org/stable/c/d315ee8a07fd1810880227319cf60e6cd925ef22","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d9ebd8f9aa8b2773235889cb903fafd61f2d8585","name":"https://git.kernel.org/stable/c/d9ebd8f9aa8b2773235889cb903fafd61f2d8585","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-90075","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90075","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4b549a2ef4bef9965d97cbd992ba67930cd3e0fe d315ee8a07fd1810880227319cf60e6cd925ef22 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4b549a2ef4bef9965d97cbd992ba67930cd3e0fe a9a5b2943a00df2ab81a2209f31dd9e87016f120 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4b549a2ef4bef9965d97cbd992ba67930cd3e0fe 3782067ec0d485628b6f1f9ede3eeeb4f611fcf2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4b549a2ef4bef9965d97cbd992ba67930cd3e0fe 397e2b1f71d9f15b8b4e47d24eb620e4dff8878d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.221 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.188 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.157 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.110 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.52 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-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_fq_codel.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"d315ee8a07fd1810880227319cf60e6cd925ef22","status":"affected","version":"4b549a2ef4bef9965d97cbd992ba67930cd3e0fe","versionType":"git"},{"lessThan":"a9a5b2943a00df2ab81a2209f31dd9e87016f120","status":"affected","version":"4b549a2ef4bef9965d97cbd992ba67930cd3e0fe","versionType":"git"},{"lessThan":"3782067ec0d485628b6f1f9ede3eeeb4f611fcf2","status":"affected","version":"4b549a2ef4bef9965d97cbd992ba67930cd3e0fe","versionType":"git"},{"lessThan":"397e2b1f71d9f15b8b4e47d24eb620e4dff8878d","status":"affected","version":"4b549a2ef4bef9965d97cbd992ba67930cd3e0fe","versionType":"git"},{"lessThan":"324f86806673ae4a55f66d28db84577f46f615e1","status":"affected","version":"4b549a2ef4bef9965d97cbd992ba67930cd3e0fe","versionType":"git"},{"lessThan":"dfb4b61db886917244284b18b44b23d2254b82c2","status":"affected","version":"4b549a2ef4bef9965d97cbd992ba67930cd3e0fe","versionType":"git"},{"lessThan":"9f499e5827fdb6d7fdb46a7ce731852f6b1a1bb9","status":"affected","version":"4b549a2ef4bef9965d97cbd992ba67930cd3e0fe","versionType":"git"},{"lessThan":"d9ebd8f9aa8b2773235889cb903fafd61f2d8585","status":"affected","version":"4b549a2ef4bef9965d97cbd992ba67930cd3e0fe","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/sched/sch_fq_codel.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"3.5"},{"lessThan":"3.5","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.270","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.221","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.188","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.157","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.110","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.52","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.270","versionStartIncluding":"3.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.221","versionStartIncluding":"3.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.188","versionStartIncluding":"3.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.157","versionStartIncluding":"3.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.110","versionStartIncluding":"3.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.52","versionStartIncluding":"3.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"3.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"3.5","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq_codel: clamp default quantum and mtu\n\nfq_codel_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) without\nclamping. A device with a huge MTU (e.g. dummy with max_mtu == 0\naccepting MTU 2147483634) makes psched_mtu() return 0x80000000, which\noverflows the signed flow->deficit to INT_MIN in fq_codel_dequeue(),\ncausing an infinite loop and soft lockup. Emulate fq_codel_change()\nand constrain to [256, FQ_CODEL_QUANTUM_MAX].\n\nThe same unclamped psched_mtu() is assigned to q->cparams.mtu a bit\nbelow, and fq_codel_change() never updates it. codel_should_drop()\ntests \"*backlog <= params->mtu\"; with mtu == 0x80000000 (~2 GiB) and\nthe default 32 MiB memory_limit, the test is always true, so CoDel is\nsilently and completely disabled (no drops, no ECN). Declare a single\nclamped mtu and assign both q->quantum and q->cparams.mtu from it,\nwhich also removes the double psched_mtu() call.\n\nConditions to recreate the bug: a device whose MTU (plus\nhard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy\ndevice with max_mtu == 0 accepting MTU 2147483634). Requires\nCAP_NET_ADMIN in a user namespace."}],"providerMetadata":{"dateUpdated":"2026-09-17T16:05:54.851Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/d315ee8a07fd1810880227319cf60e6cd925ef22"},{"url":"https://git.kernel.org/stable/c/a9a5b2943a00df2ab81a2209f31dd9e87016f120"},{"url":"https://git.kernel.org/stable/c/3782067ec0d485628b6f1f9ede3eeeb4f611fcf2"},{"url":"https://git.kernel.org/stable/c/397e2b1f71d9f15b8b4e47d24eb620e4dff8878d"},{"url":"https://git.kernel.org/stable/c/324f86806673ae4a55f66d28db84577f46f615e1"},{"url":"https://git.kernel.org/stable/c/dfb4b61db886917244284b18b44b23d2254b82c2"},{"url":"https://git.kernel.org/stable/c/9f499e5827fdb6d7fdb46a7ce731852f6b1a1bb9"},{"url":"https://git.kernel.org/stable/c/d9ebd8f9aa8b2773235889cb903fafd61f2d8585"}],"title":"net/sched: fq_codel: clamp default quantum and mtu","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-90075","datePublished":"2026-09-17T16:05:54.851Z","dateReserved":"2026-09-11T19:38:34.785Z","dateUpdated":"2026-09-17T16:05:54.851Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-17 17:16:56","lastModifiedDate":"2026-09-17 17:16:56","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"90075","Ordinal":"1","Title":"net/sched: fq_codel: clamp default quantum and mtu","CVE":"CVE-2026-90075","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"90075","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq_codel: clamp default quantum and mtu\n\nfq_codel_init() sets q->quantum = psched_mtu(qdisc_dev(sch)) without\nclamping. A device with a huge MTU (e.g. dummy with max_mtu == 0\naccepting MTU 2147483634) makes psched_mtu() return 0x80000000, which\noverflows the signed flow->deficit to INT_MIN in fq_codel_dequeue(),\ncausing an infinite loop and soft lockup. Emulate fq_codel_change()\nand constrain to [256, FQ_CODEL_QUANTUM_MAX].\n\nThe same unclamped psched_mtu() is assigned to q->cparams.mtu a bit\nbelow, and fq_codel_change() never updates it. codel_should_drop()\ntests \"*backlog <= params->mtu\"; with mtu == 0x80000000 (~2 GiB) and\nthe default 32 MiB memory_limit, the test is always true, so CoDel is\nsilently and completely disabled (no drops, no ECN). Declare a single\nclamped mtu and assign both q->quantum and q->cparams.mtu from it,\nwhich also removes the double psched_mtu() call.\n\nConditions to recreate the bug: a device whose MTU (plus\nhard_header_len) wraps psched_mtu() into the sign bit (e.g. a dummy\ndevice with max_mtu == 0 accepting MTU 2147483634). Requires\nCAP_NET_ADMIN in a user namespace.","Type":"Description","Title":"net/sched: fq_codel: clamp default quantum and mtu"}]}}}