{"id":"CVE-2026-74739","summary":"net/sched: cls_u32: skip hash tables in u32_bind_class()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_u32: skip hash tables in u32_bind_class()\n\nu32_walk() enumerates both struct tc_u_hnode and struct tc_u_knode\nthrough the walker callback. u32_bind_class() unconditionally casts the\npassed fh to tc_u_knode and accesses &n-\u003eres, so when fh is actually a\ntc_u_hnode, which has no tcf_result member, this results in a\nslab-out-of-bounds read of res-\u003eclassid in tc_cls_bind_class().\n\nThe issue can be reproduced with the following commands:\n\n    tc qdisc add dev lo root handle 1: hfsc\n    tc class add dev lo parent 1: classid 1:1 hfsc sc rate 1000kbit\n    tc filter add dev lo parent 1:1 protocol ip prio 1 u32 match u32 0 0 flowid 1:1\n    tc class add dev lo parent 1: classid 1:2 hfsc sc rate 2000kbit\n\nFix this by skipping hash tables via the TC_U32_KEY(handle) check.","modified":"2026-08-28T03:47:16.144489291Z","published":"2026-08-26T14:36:51.746Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74739.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/19d114b93c94bdef70496f26685c2a6b242f41b3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/31f26a95eeee926946809ac456c61a3217936a62"},{"type":"WEB","url":"https://git.kernel.org/stable/c/594a064d603202b9ee21e07679d854e5c1750cc4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6d3724e616faf952c3adcf8414fc21a828ef3709"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e71f8e9ed6f311410b14741f6012afe01869c0fa"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ec5f3005586a785689fd568361b0c5925cb1548b"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74739.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74739"},{"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":"07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1"},{"fixed":"ec5f3005586a785689fd568361b0c5925cb1548b"},{"fixed":"19d114b93c94bdef70496f26685c2a6b242f41b3"},{"fixed":"594a064d603202b9ee21e07679d854e5c1750cc4"},{"fixed":"31f26a95eeee926946809ac456c61a3217936a62"},{"fixed":"e71f8e9ed6f311410b14741f6012afe01869c0fa"},{"fixed":"6d3724e616faf952c3adcf8414fc21a828ef3709"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74739.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.14.0"},{"fixed":"6.1.184"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.153"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.105"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.46"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.10"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74739.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}