{"id":"CVE-2026-97959","state":"PUBLISHED","title":"net/sched: cls_route: free emptied bucket on filter move","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_route: free emptied bucket on filter move\n\nroute4_change can move an existing filter to a different top-level\nbucket: route4_set_parms recomputes the handle from TCA_ROUTE4_TO/\nFROM/IIF, and the handle-mismatch check is gated on the 'new' flag, so\nfor an existing filter the new handle may differ from the old one and\nland in a different bucket. When this happens, the filter is unlinked\nfrom the old bucket, but the bucket itself is never freed once it goes\nempty. The stale empty bucket remains in head->table[], causing\nroute4_delete to report *last=false even after the last live filter is\ngone. That pins the empty tcf_proto and causes a leak.\n\nFix this by refcounting the filters linked to a bucket and freeing the\nbucket when the count drops to zero. The existing scan in route4_delete\ngoes away with it.\n\nThe count is updated at all sites that link or unlink a filter during add,\nchange and delete, and the bucket is dropped from head->table[] as soon as\nit reaches zero.\n\nConditions to recreate the bug:\n  CONFIG_NET_CLS_ROUTE4=y, CONFIG_NET_SCH_INGRESS=y, CONFIG_NET_CLS_ACT=y.\n\n  tc qdisc replace dev lo clsact\n  tc filter add dev lo ingress protocol ip pref 100 route from 1 to 1\n  tc filter change dev lo ingress protocol ip pref 100 handle 0x10001 \\\n    route from 1 to 2\n  tc filter del dev lo ingress protocol ip pref 100 handle 0x10002 \\\n    route from 1 to 2\n  tc filter show dev lo ingress | grep -c 'pref 100 route chain 0 '","publishedAt":"2026-09-25T10:23:04.348Z","updatedAt":"2026-10-19T09:11:25.255Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"9e7741b41a25b9d49df4d262fa314342e6f95c50","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"48d38bf8c22a05fde07ba1f885cde27b851649a2","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"cc99d26b12431e4e4d0e346ec32764eb42c0aed9","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"41e94079200aaf0cdbe4594b0af75710b33da124","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"2e2f130951d34871b0643bf700164d97cff4b427","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"f8495d67434e1cb7e511297687ca55fdb28e4c20","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"81dd117c04422c6d0c7974aba9fa6a0ba370959b","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"1853f30cf5c84971f99788a76207c6f745380896","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/cls_route.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.1","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/cls_route.c"]}],"references":["https://git.kernel.org/stable/c/9e7741b41a25b9d49df4d262fa314342e6f95c50","https://git.kernel.org/stable/c/48d38bf8c22a05fde07ba1f885cde27b851649a2","https://git.kernel.org/stable/c/cc99d26b12431e4e4d0e346ec32764eb42c0aed9","https://git.kernel.org/stable/c/41e94079200aaf0cdbe4594b0af75710b33da124","https://git.kernel.org/stable/c/2e2f130951d34871b0643bf700164d97cff4b427","https://git.kernel.org/stable/c/f8495d67434e1cb7e511297687ca55fdb28e4c20","https://git.kernel.org/stable/c/81dd117c04422c6d0c7974aba9fa6a0ba370959b","https://git.kernel.org/stable/c/1853f30cf5c84971f99788a76207c6f745380896"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/97xxx/CVE-2026-97959.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-97959","state":"PUBLISHED","datePublished":"2026-09-25T10:23:04.348Z","dateUpdated":"2026-10-19T09:11:25.255Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:18:58.205Z"},"containers":{"cna":{"title":"net/sched: cls_route: free emptied bucket on filter move","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_route: free emptied bucket on filter move\n\nroute4_change can move an existing filter to a different top-level\nbucket: route4_set_parms recomputes the handle from TCA_ROUTE4_TO/\nFROM/IIF, and the handle-mismatch check is gated on the 'new' flag, so\nfor an existing filter the new handle may differ from the old one and\nland in a different bucket. When this happens, the filter is unlinked\nfrom the old bucket, but the bucket itself is never freed once it goes\nempty. The stale empty bucket remains in head->table[], causing\nroute4_delete to report *last=false even after the last live filter is\ngone. That pins the empty tcf_proto and causes a leak.\n\nFix this by refcounting the filters linked to a bucket and freeing the\nbucket when the count drops to zero. The existing scan in route4_delete\ngoes away with it.\n\nThe count is updated at all sites that link or unlink a filter during add,\nchange and delete, and the bucket is dropped from head->table[] as soon as\nit reaches zero.\n\nConditions to recreate the bug:\n  CONFIG_NET_CLS_ROUTE4=y, CONFIG_NET_SCH_INGRESS=y, CONFIG_NET_CLS_ACT=y.\n\n  tc qdisc replace dev lo clsact\n  tc filter add dev lo ingress protocol ip pref 100 route from 1 to 1\n  tc filter change dev lo ingress protocol ip pref 100 handle 0x10001 \\\n    route from 1 to 2\n  tc filter del dev lo ingress protocol ip pref 100 handle 0x10002 \\\n    route from 1 to 2\n  tc filter show dev lo ingress | grep -c 'pref 100 route chain 0 '"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"9e7741b41a25b9d49df4d262fa314342e6f95c50","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"48d38bf8c22a05fde07ba1f885cde27b851649a2","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"cc99d26b12431e4e4d0e346ec32764eb42c0aed9","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"41e94079200aaf0cdbe4594b0af75710b33da124","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"2e2f130951d34871b0643bf700164d97cff4b427","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"f8495d67434e1cb7e511297687ca55fdb28e4c20","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"81dd117c04422c6d0c7974aba9fa6a0ba370959b","versionType":"git"},{"version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","status":"affected","lessThan":"1853f30cf5c84971f99788a76207c6f745380896","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/cls_route.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.1","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/cls_route.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9e7741b41a25b9d49df4d262fa314342e6f95c50"},{"url":"https://git.kernel.org/stable/c/48d38bf8c22a05fde07ba1f885cde27b851649a2"},{"url":"https://git.kernel.org/stable/c/cc99d26b12431e4e4d0e346ec32764eb42c0aed9"},{"url":"https://git.kernel.org/stable/c/41e94079200aaf0cdbe4594b0af75710b33da124"},{"url":"https://git.kernel.org/stable/c/2e2f130951d34871b0643bf700164d97cff4b427"},{"url":"https://git.kernel.org/stable/c/f8495d67434e1cb7e511297687ca55fdb28e4c20"},{"url":"https://git.kernel.org/stable/c/81dd117c04422c6d0c7974aba9fa6a0ba370959b"},{"url":"https://git.kernel.org/stable/c/1853f30cf5c84971f99788a76207c6f745380896"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:11:25.255Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"5.10.271"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"5.15.222"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.12.111"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.18.53"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"7.2.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}