{"id":"CVE-2026-90074","summary":"net/sched: fq_pie: clamp default quantum to avoid signed overflow","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: fq_pie: clamp default quantum to avoid signed overflow\n\nfq_pie_init() sets q-\u003equantum = 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-\u003edeficit to INT_MIN in fq_pie_qdisc_dequeue(),\ncausing an infinite loop and soft lockup. Emulate fq_pie_policy which\nis already bounded to [1, 1 \u003c\u003c 20]; clamp the default to [256, 1 \u003c\u003c 20].\n256 matches fq_codel's floor and is a sane minimum for a DRR quantum.\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.","modified":"2026-09-19T03:47:24.128379198Z","published":"2026-09-17T16:05:54.214Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90074.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/044fa2498bbc2900f0c48a6ef2fdd5b2bdfc3795"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1f43e4dbc93b7d02761a024d5f895df823c07b72"},{"type":"WEB","url":"https://git.kernel.org/stable/c/435da3734a8e63d3067016accc977ed1d10aaaa0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/44dad8fe99b58a7fe2961e9eec6a5f07ace5b51f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6f1be05faecef4c0f9a008200209f66ef2e133f7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bf97fd2163ad1191ef8daa3d4df8372aee19e396"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c86cd7ed0b0e44779a3d1683f03e4353baf4bdc9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f7942b2693bc24c7d609a03d06f97bee3b0bd96a"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90074.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90074"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ec97ecf1ebe485a17cd8395a5f35e6b80b57665a"},{"fixed":"1f43e4dbc93b7d02761a024d5f895df823c07b72"},{"fixed":"f7942b2693bc24c7d609a03d06f97bee3b0bd96a"},{"fixed":"6f1be05faecef4c0f9a008200209f66ef2e133f7"},{"fixed":"435da3734a8e63d3067016accc977ed1d10aaaa0"},{"fixed":"44dad8fe99b58a7fe2961e9eec6a5f07ace5b51f"},{"fixed":"044fa2498bbc2900f0c48a6ef2fdd5b2bdfc3795"},{"fixed":"bf97fd2163ad1191ef8daa3d4df8372aee19e396"},{"fixed":"c86cd7ed0b0e44779a3d1683f03e4353baf4bdc9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90074.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.6.0"},{"fixed":"5.10.270"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.221"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.188"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.52"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90074.json"}}],"schema_version":"1.9.0"}