{"id":"CVE-2026-98011","state":"PUBLISHED","title":"net/sched: hhf: clamp quantum in change and init paths","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: hhf: clamp quantum in change and init paths\n\nhhf_change() accepts any quantum from userspace, including 1. With a\ncrafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 makes\nthe deficit-refill loop spin ~2^31 times under the qdisc lock\n(a soft lockup / denial of service).\n\nAdd max(256U, ...) in hhf_change() matching fq_codel_change(). Clamp\nhhf_init() to [256, 1<<20] matching the siblings, and remove the old\nfallback that only set quantum=256 on overflow.\n\nConditions to recreate the bug:\n  CONFIG_NET_SCH_HHF=y. Requires CAP_NET_ADMIN (namespace-local via\n  unshare -Urn suffices).\n\n  tc qdisc add dev dummy0 root hhf\n  tc qdisc change dev dummy0 root hhf quantum 1 stab data 32768 size_log 15 cell_log 0","publishedAt":"2026-09-25T10:23:35.338Z","updatedAt":"2026-10-19T09:12:16.718Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"a328698d046098e6f55b3b1460cac6bab577be58","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"c364ad3ab3c8a6bce469a5cbf02881ab1324c5da","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"2c6dd9fc86d446a03728c43f3b96d9ae29aa058f","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"6570f326a6a96bedf3d1d1dab6acc9f8c29104ec","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"1113b674307ffddd402524bd1fd9d7d5629b705b","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"2e77947bbf6c166e76c038663832d0914418f761","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"0898c6f9fa9ce2632ae88bd0f34a878ccc6335af","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"eb56a495f59baf6cad5ed80e3ffb9078098b1346","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_hhf.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.14","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.7","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_hhf.c"]}],"references":["https://git.kernel.org/stable/c/a328698d046098e6f55b3b1460cac6bab577be58","https://git.kernel.org/stable/c/c364ad3ab3c8a6bce469a5cbf02881ab1324c5da","https://git.kernel.org/stable/c/2c6dd9fc86d446a03728c43f3b96d9ae29aa058f","https://git.kernel.org/stable/c/6570f326a6a96bedf3d1d1dab6acc9f8c29104ec","https://git.kernel.org/stable/c/1113b674307ffddd402524bd1fd9d7d5629b705b","https://git.kernel.org/stable/c/2e77947bbf6c166e76c038663832d0914418f761","https://git.kernel.org/stable/c/0898c6f9fa9ce2632ae88bd0f34a878ccc6335af","https://git.kernel.org/stable/c/eb56a495f59baf6cad5ed80e3ffb9078098b1346"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98011.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98011","state":"PUBLISHED","datePublished":"2026-09-25T10:23:35.338Z","dateUpdated":"2026-10-19T09:12:16.718Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:19:56.069Z"},"containers":{"cna":{"title":"net/sched: hhf: clamp quantum in change and init paths","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: hhf: clamp quantum in change and init paths\n\nhhf_change() accepts any quantum from userspace, including 1. With a\ncrafted size table qdisc_pkt_len reaches ~2 GiB, so quantum=1 makes\nthe deficit-refill loop spin ~2^31 times under the qdisc lock\n(a soft lockup / denial of service).\n\nAdd max(256U, ...) in hhf_change() matching fq_codel_change(). Clamp\nhhf_init() to [256, 1<<20] matching the siblings, and remove the old\nfallback that only set quantum=256 on overflow.\n\nConditions to recreate the bug:\n  CONFIG_NET_SCH_HHF=y. Requires CAP_NET_ADMIN (namespace-local via\n  unshare -Urn suffices).\n\n  tc qdisc add dev dummy0 root hhf\n  tc qdisc change dev dummy0 root hhf quantum 1 stab data 32768 size_log 15 cell_log 0"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"a328698d046098e6f55b3b1460cac6bab577be58","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"c364ad3ab3c8a6bce469a5cbf02881ab1324c5da","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"2c6dd9fc86d446a03728c43f3b96d9ae29aa058f","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"6570f326a6a96bedf3d1d1dab6acc9f8c29104ec","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"1113b674307ffddd402524bd1fd9d7d5629b705b","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"2e77947bbf6c166e76c038663832d0914418f761","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"0898c6f9fa9ce2632ae88bd0f34a878ccc6335af","versionType":"git"},{"version":"10239edf86f137ce4c39b62ea9575e8053c549a0","status":"affected","lessThan":"eb56a495f59baf6cad5ed80e3ffb9078098b1346","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_hhf.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.14","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.111","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.53","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.7","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_hhf.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/a328698d046098e6f55b3b1460cac6bab577be58"},{"url":"https://git.kernel.org/stable/c/c364ad3ab3c8a6bce469a5cbf02881ab1324c5da"},{"url":"https://git.kernel.org/stable/c/2c6dd9fc86d446a03728c43f3b96d9ae29aa058f"},{"url":"https://git.kernel.org/stable/c/6570f326a6a96bedf3d1d1dab6acc9f8c29104ec"},{"url":"https://git.kernel.org/stable/c/1113b674307ffddd402524bd1fd9d7d5629b705b"},{"url":"https://git.kernel.org/stable/c/2e77947bbf6c166e76c038663832d0914418f761"},{"url":"https://git.kernel.org/stable/c/0898c6f9fa9ce2632ae88bd0f34a878ccc6335af"},{"url":"https://git.kernel.org/stable/c/eb56a495f59baf6cad5ed80e3ffb9078098b1346"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:12:16.718Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"5.10.271"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"5.15.222"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.12.111"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"6.18.53"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"7.2.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.14","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}