{"id":"CVE-2026-98234","summary":"net/sched: hhf: cap hh_flows_limit at change time","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: hhf: cap hh_flows_limit at change time\n\nhhf_change() stores TCA_HHF_HH_FLOWS_LIMIT with no upper bound. A huge\nhh_flows_limit lets each new heavy-hitter flow pass the\nhh_flows_current_cnt check in alloc_new_hh() and forces a fixed-size\nkzalloc(GFP_ATOMIC) per flow under spoofed traffic, for unbounded memory\ngrowth.\n\nBound the attribute with NLA_POLICY_MAX() at 2*HH_FLOWS_CNT (the\nhhf_init() default) and report the rejected value via extack. The\ndeprecated nested parse is kept: legacy tc does not set NLA_F_NESTED on\nTCA_OPTIONS. Configs relying on hh_limit above the default were relying\non unbounded, unsafe behaviour and are not supported going forward.\n\nhhf_init() also ran hhf_change() before setting the default\nhh_flows_limit, so a user-supplied hh_limit at add time was clobbered\nback to 2048. Set the default before hhf_change() so the configured\nvalue sticks.\n\nThis is a follow-up to commit eb56a495f59b (\"net/sched: hhf: clamp\nquantum in change and init paths\"), which bounded the quantum of the\nsame qdisc; the hh_flows_limit bound is the remaining unbounded knob of\nthat series' scope.\n\nConditions to recreate the bug: CAP_NET_ADMIN in a user namespace;\ntc qdisc change dev X root hhf hh_limit 4294967295 succeeds and the\nvalue is echoed by tc qdisc show, unbounding heavy-hitter flow\nallocations; also tc qdisc add dev X root hhf hh_limit 500 stores 2048\ninstead of 500.","modified":"2026-10-07T02:47:30.178725655Z","published":"2026-10-06T08:45:07.215Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98234.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/06d2a101e89063cb0b9b459104db48bdfb0a797d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1731ff1d20489afe4cd01b7d16d37f324746ac54"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2cef2588c995722a901368def30befeef9ae55c6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/35fd423a5c5132c6f4321f6c4f0a7b4b90af830c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7adfd0a42174b85c6bd678858ecd6674f403f336"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d8e2f1f0263b7c97b222c06070cccf13e0ab7112"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f3f4a5cb4a6e9b1f1f25d34dfc25f836a1601db4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f6547d27ce2093c5627636fb63dd0b7523c466f9"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98234.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98234"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"10239edf86f137ce4c39b62ea9575e8053c549a0"},{"fixed":"7adfd0a42174b85c6bd678858ecd6674f403f336"},{"fixed":"35fd423a5c5132c6f4321f6c4f0a7b4b90af830c"},{"fixed":"06d2a101e89063cb0b9b459104db48bdfb0a797d"},{"fixed":"d8e2f1f0263b7c97b222c06070cccf13e0ab7112"},{"fixed":"f3f4a5cb4a6e9b1f1f25d34dfc25f836a1601db4"},{"fixed":"1731ff1d20489afe4cd01b7d16d37f324746ac54"},{"fixed":"f6547d27ce2093c5627636fb63dd0b7523c466f9"},{"fixed":"2cef2588c995722a901368def30befeef9ae55c6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98234.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.14.0"},{"fixed":"5.10.271"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.222"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.189"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.158"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.112"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.54"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.8"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98234.json"}}],"schema_version":"1.9.0"}