{"id":"CVE-2026-98012","state":"PUBLISHED","title":"net/sched: sfq: clamp quantum in change path","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sfq: clamp quantum in change path\n\nsfq_change() accepts any non-negative quantum (only rejects\n(int)ctl->quantum < 0). With a crafted size table qdisc_pkt_len reaches\n~2 GiB, so quantum=1 makes the deficit-refill loop spin ~2^31 times\nunder the qdisc lock (a soft lockup / denial of service).\n\nAdd max(256U, ...) matching fq_codel_change(). Reject quantum > 1<<20\nwith -EINVAL, matching fq_codel_change() and the init clamp.\n\nConditions to recreate the bug:\n  CONFIG_NET_SCH_SFQ=y. Requires CAP_NET_ADMIN (namespace-local via\n  unshare -Urn suffices).\n\n  tc qdisc add dev dummy0 root sfq\n  tc qdisc change dev dummy0 root sfq quantum 1 stab data 32768 size_log 15 cell_log 0","publishedAt":"2026-09-25T10:23:35.934Z","updatedAt":"2026-10-19T09:12:17.681Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4919649699c5f4dbae08b8e2ed536fc9d6c3c2aa","status":"affected","lessThan":"4117c528b2de5fdc3e4a7e3626815b616a635cdc","versionType":"git"},{"version":"548cf048b426729a7a1fa6acd1271c010c9a7380","status":"affected","lessThan":"f82fa6f10d4a69322cad0f7a4aa523ce6292a5a0","versionType":"git"},{"version":"c49ac48fac51a6a54efd5963954d02bacf075085","status":"affected","lessThan":"0692ce5a528df450d64e9f819054177e9d91076f","versionType":"git"},{"version":"58ae7465f0e7113d45aa88a66bf2d203c71c195e","status":"affected","lessThan":"e4192bcf83aaab02129644ddf4656fd86e93751f","versionType":"git"},{"version":"82bd38bd5467ece1ee274b493f51326cf5220a5a","status":"affected","lessThan":"f3820dce042a673fcb28cc31c87ee14257e21a17","versionType":"git"},{"version":"e4650d7ae4252f67e997a632adfae0dd74d3a99a","status":"affected","lessThan":"534cd7ecbbc6e8a974f4003a5c1557439c6e0a72","versionType":"git"},{"version":"e4650d7ae4252f67e997a632adfae0dd74d3a99a","status":"affected","lessThan":"e6c1cb728e389354203a72bc77464c222a247aeb","versionType":"git"},{"version":"e4650d7ae4252f67e997a632adfae0dd74d3a99a","status":"affected","lessThan":"fb9f88a33c516ea5c0bcd9a22ca288b246b34567","versionType":"git"},{"version":"843cacb88f42f426973f1ed11c6fb562558efb27","status":"affected","versionType":"git"},{"version":"5.10.239","status":"affected","lessThan":"5.10.271","versionType":"semver"},{"version":"5.15.186","status":"affected","lessThan":"5.15.222","versionType":"semver"},{"version":"6.1.129","status":"affected","lessThan":"6.1.189","versionType":"semver"},{"version":"6.6.76","status":"affected","lessThan":"6.6.158","versionType":"semver"},{"version":"6.12.13","status":"affected","lessThan":"6.12.111","versionType":"semver"},{"version":"5.4.297","status":"affected","lessThan":"5.5","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_sfq.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.13","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_sfq.c"]}],"references":["https://git.kernel.org/stable/c/4117c528b2de5fdc3e4a7e3626815b616a635cdc","https://git.kernel.org/stable/c/f82fa6f10d4a69322cad0f7a4aa523ce6292a5a0","https://git.kernel.org/stable/c/0692ce5a528df450d64e9f819054177e9d91076f","https://git.kernel.org/stable/c/e4192bcf83aaab02129644ddf4656fd86e93751f","https://git.kernel.org/stable/c/f3820dce042a673fcb28cc31c87ee14257e21a17","https://git.kernel.org/stable/c/534cd7ecbbc6e8a974f4003a5c1557439c6e0a72","https://git.kernel.org/stable/c/e6c1cb728e389354203a72bc77464c222a247aeb","https://git.kernel.org/stable/c/fb9f88a33c516ea5c0bcd9a22ca288b246b34567"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98012.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98012","state":"PUBLISHED","datePublished":"2026-09-25T10:23:35.934Z","dateUpdated":"2026-10-19T09:12:17.681Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:19:56.069Z"},"containers":{"cna":{"title":"net/sched: sfq: clamp quantum in change path","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sfq: clamp quantum in change path\n\nsfq_change() accepts any non-negative quantum (only rejects\n(int)ctl->quantum < 0). With a crafted size table qdisc_pkt_len reaches\n~2 GiB, so quantum=1 makes the deficit-refill loop spin ~2^31 times\nunder the qdisc lock (a soft lockup / denial of service).\n\nAdd max(256U, ...) matching fq_codel_change(). Reject quantum > 1<<20\nwith -EINVAL, matching fq_codel_change() and the init clamp.\n\nConditions to recreate the bug:\n  CONFIG_NET_SCH_SFQ=y. Requires CAP_NET_ADMIN (namespace-local via\n  unshare -Urn suffices).\n\n  tc qdisc add dev dummy0 root sfq\n  tc qdisc change dev dummy0 root sfq quantum 1 stab data 32768 size_log 15 cell_log 0"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4919649699c5f4dbae08b8e2ed536fc9d6c3c2aa","status":"affected","lessThan":"4117c528b2de5fdc3e4a7e3626815b616a635cdc","versionType":"git"},{"version":"548cf048b426729a7a1fa6acd1271c010c9a7380","status":"affected","lessThan":"f82fa6f10d4a69322cad0f7a4aa523ce6292a5a0","versionType":"git"},{"version":"c49ac48fac51a6a54efd5963954d02bacf075085","status":"affected","lessThan":"0692ce5a528df450d64e9f819054177e9d91076f","versionType":"git"},{"version":"58ae7465f0e7113d45aa88a66bf2d203c71c195e","status":"affected","lessThan":"e4192bcf83aaab02129644ddf4656fd86e93751f","versionType":"git"},{"version":"82bd38bd5467ece1ee274b493f51326cf5220a5a","status":"affected","lessThan":"f3820dce042a673fcb28cc31c87ee14257e21a17","versionType":"git"},{"version":"e4650d7ae4252f67e997a632adfae0dd74d3a99a","status":"affected","lessThan":"534cd7ecbbc6e8a974f4003a5c1557439c6e0a72","versionType":"git"},{"version":"e4650d7ae4252f67e997a632adfae0dd74d3a99a","status":"affected","lessThan":"e6c1cb728e389354203a72bc77464c222a247aeb","versionType":"git"},{"version":"e4650d7ae4252f67e997a632adfae0dd74d3a99a","status":"affected","lessThan":"fb9f88a33c516ea5c0bcd9a22ca288b246b34567","versionType":"git"},{"version":"843cacb88f42f426973f1ed11c6fb562558efb27","status":"affected","versionType":"git"},{"version":"5.10.239","status":"affected","lessThan":"5.10.271","versionType":"semver"},{"version":"5.15.186","status":"affected","lessThan":"5.15.222","versionType":"semver"},{"version":"6.1.129","status":"affected","lessThan":"6.1.189","versionType":"semver"},{"version":"6.6.76","status":"affected","lessThan":"6.6.158","versionType":"semver"},{"version":"6.12.13","status":"affected","lessThan":"6.12.111","versionType":"semver"},{"version":"5.4.297","status":"affected","lessThan":"5.5","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_sfq.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.13","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_sfq.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/4117c528b2de5fdc3e4a7e3626815b616a635cdc"},{"url":"https://git.kernel.org/stable/c/f82fa6f10d4a69322cad0f7a4aa523ce6292a5a0"},{"url":"https://git.kernel.org/stable/c/0692ce5a528df450d64e9f819054177e9d91076f"},{"url":"https://git.kernel.org/stable/c/e4192bcf83aaab02129644ddf4656fd86e93751f"},{"url":"https://git.kernel.org/stable/c/f3820dce042a673fcb28cc31c87ee14257e21a17"},{"url":"https://git.kernel.org/stable/c/534cd7ecbbc6e8a974f4003a5c1557439c6e0a72"},{"url":"https://git.kernel.org/stable/c/e6c1cb728e389354203a72bc77464c222a247aeb"},{"url":"https://git.kernel.org/stable/c/fb9f88a33c516ea5c0bcd9a22ca288b246b34567"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:12:17.681Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.239","versionEndExcluding":"5.10.271"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.186","versionEndExcluding":"5.15.222"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.129","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.76","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.13","versionEndExcluding":"6.12.111"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.18.53"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"7.2.7"},{"vulnerable":true,"criteria":"cpe: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