{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98017","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:19:56.069Z","datePublished":"2026-09-25T10:23:39.107Z","dateUpdated":"2026-10-03T11:01:38.454Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-03T11:01:38.454Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: defer qdisc freeing after failed creation\n\nAn RTM_NEWQDISC request can make clsact bind a populated shared ingress\nblock during ->init(), publishing an embedded mini_Qdisc to lockless\nreaders.  If the same request has an invalid TCA_RATE, estimator setup\nfails after ->init(); the unwind removes the pointer but synchronously\nfrees its containing qdisc while tc_run() may still hold it.\n\nRetire failed qdiscs through the same RCU helper as normal destruction.\nInline the synchronous free into the callback now that no direct callers\nremain."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The trigger is a local rtnetlink RTM_NEWQDISC message (tc_modify_qdisc -> qdisc_create) with a clsact kind, a shared TCA_INGRESS_BLOCK and an invalid TCA_RATE. Packets only drive the reader side (tc_run), and no remote peer supplies the input that causes the bug.\nAC:L - The attacker controls both sides of the race: they repeat the failing clsact create, which runs qdisc_free() with no grace period, while pushing traffic through their own veth/dummy device so that tc_run() dereferences the published miniq. No outside condition is needed.\nPR:L - tc_modify_qdisc only needs CAP_NET_ADMIN in the netns that owns the device, which an unprivileged user gets through unshare -Urn plus a self-created veth/dummy interface. That makes it reachable as PR:L rather than requiring init-namespace root.\nUI:N - The attacker performs every step themselves: creating the shared block and filter, sending the failing RTM_NEWQDISC, and generating traffic. No victim action is needed.\nS:U - The use-after-free and any resulting privilege escalation stay inside the same kernel security authority. No hypervisor or IOMMU boundary is crossed.\nC:H - The mini_Qdisc embedded in the freed qdisc (a kmalloc'd object, so its slot can be reclaimed) is read by tc_run: miniq->block and miniq->filter_list are passed to tcf_classify. With a sprayed replacement object, the attacker controls these pointers, which can be used to leak kernel memory.\nI:H - tc_run calls mini_qdisc_bstats_cpu_update(), which writes through the cpu_bstats pointer taken from the freed object, and tcf_classify follows a filter_list the attacker can control. After reclaim, this gives a controlled write and a path to hijacking control flow.\nA:H - Freeing the qdisc while RCU readers in tc_run still hold its embedded miniq leads to KASAN splats and oopses when the packet path touches the freed or reallocated memory. The result is a kernel crash."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/sch_generic.h","net/sched/sch_api.c","net/sched/sch_generic.c"],"versions":[{"version":"51ab2994c387c80b45caf8b8067b3f3b97771d25","lessThan":"96a27a3e64e7c87abade03fb2ad04ed66992a89a","status":"affected","versionType":"git"},{"version":"51ab2994c387c80b45caf8b8067b3f3b97771d25","lessThan":"6a1b49bb9fdf9e8e7aa38e8cd635c0cc4074447d","status":"affected","versionType":"git"},{"version":"51ab2994c387c80b45caf8b8067b3f3b97771d25","lessThan":"20bf6fa34b345333971bd4464a322cce87b83f4e","status":"affected","versionType":"git"},{"version":"51ab2994c387c80b45caf8b8067b3f3b97771d25","lessThan":"156a3bab69744e9225bb9eff8c5cc53da18d5a2e","status":"affected","versionType":"git"},{"version":"51ab2994c387c80b45caf8b8067b3f3b97771d25","lessThan":"5bfe927c5b4b290fad529186218c728589b4b101","status":"affected","versionType":"git"},{"version":"51ab2994c387c80b45caf8b8067b3f3b97771d25","lessThan":"e6662f2100f8d33b0f4d0047c219efd6bba186ea","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/sch_generic.h","net/sched/sch_api.c","net/sched/sch_generic.c"],"versions":[{"version":"4.16","status":"affected"},{"version":"0","lessThan":"4.16","status":"unaffected","versionType":"semver"},{"version":"6.1.189","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.158","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.111","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.53","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.7","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.12.111"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.18.53"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"7.2.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"7.3-rc3"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/96a27a3e64e7c87abade03fb2ad04ed66992a89a"},{"url":"https://git.kernel.org/stable/c/6a1b49bb9fdf9e8e7aa38e8cd635c0cc4074447d"},{"url":"https://git.kernel.org/stable/c/20bf6fa34b345333971bd4464a322cce87b83f4e"},{"url":"https://git.kernel.org/stable/c/156a3bab69744e9225bb9eff8c5cc53da18d5a2e"},{"url":"https://git.kernel.org/stable/c/5bfe927c5b4b290fad529186218c728589b4b101"},{"url":"https://git.kernel.org/stable/c/e6662f2100f8d33b0f4d0047c219efd6bba186ea"}],"title":"net/sched: defer qdisc freeing after failed creation","x_generator":{"engine":"bippy-1.2.0"}}}}