{"id":"CVE-2026-74739","title":"net/sched: cls_u32: skip hash tables in u32_bind_class()","summary":"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…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < ec5f3005586a785689fd568361b0c5925cb1548b","Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 19d114b93c94bdef70496f26685c2a6b242f41b3","Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 594a064d603202b9ee21e07679d854e5c1750cc4","Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 31f26a95eeee926946809ac456c61a3217936a62","Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < e71f8e9ed6f311410b14741f6012afe01869c0fa","Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 6d3724e616faf952c3adcf8414fc21a828ef3709","Linux 4.14"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T19:15:59.810780Z"},"published":"2026-08-26","updated":"2026-10-16","sourceUpdated":"2026-10-16T19:16:12.856Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74739","references":[{"url":"https://git.kernel.org/stable/c/ec5f3005586a785689fd568361b0c5925cb1548b"},{"url":"https://git.kernel.org/stable/c/19d114b93c94bdef70496f26685c2a6b242f41b3"},{"url":"https://git.kernel.org/stable/c/594a064d603202b9ee21e07679d854e5c1750cc4"},{"url":"https://git.kernel.org/stable/c/31f26a95eeee926946809ac456c61a3217936a62"},{"url":"https://git.kernel.org/stable/c/e71f8e9ed6f311410b14741f6012afe01869c0fa"},{"url":"https://git.kernel.org/stable/c/6d3724e616faf952c3adcf8414fc21a828ef3709"}],"tags":["cve.org"],"epss":0.00139,"epssPercentile":0.02893,"ingestedAt":"2026-10-16T19:46:24.327Z","slug":"CVE-2026-74739","body":"## Overview\n\nIn 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->res, 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->classid 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.\n\n## Affected\n\n- `Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < ec5f3005586a785689fd568361b0c5925cb1548b`\n- `Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 19d114b93c94bdef70496f26685c2a6b242f41b3`\n- `Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 594a064d603202b9ee21e07679d854e5c1750cc4`\n- `Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 31f26a95eeee926946809ac456c61a3217936a62`\n- `Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < e71f8e9ed6f311410b14741f6012afe01869c0fa`\n- `Linux >= 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 < 6d3724e616faf952c3adcf8414fc21a828ef3709`\n- `Linux 4.14`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}