{"id":"AZL-101846","summary":"CVE-2026-90075 affecting package kernel 6.6.150.1-1","details":"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-\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_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-\u003ecparams.mtu a bit\nbelow, and fq_codel_change() never updates it. codel_should_drop()\ntests \"*backlog \u003c= params-\u003emtu\"; 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-\u003equantum and q-\u003ecparams.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.","modified":"2026-09-18T14:15:31.120713285Z","published":"2026-09-17T17:16:56Z","upstream":["CVE-2026-90075"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90075"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.150.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-101846.json"}}],"schema_version":"1.9.0"}