{"api_version":"1","generated_at":"2026-09-25T12:40:49+00:00","cve":"CVE-2026-97959","urls":{"html":"https://cve.report/CVE-2026-97959","api":"https://cve.report/api/cve/CVE-2026-97959.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-97959","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-97959"},"summary":{"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 '","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-25 11:17:23","updated_at":"2026-09-25 11:17:23"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/81dd117c04422c6d0c7974aba9fa6a0ba370959b","name":"https://git.kernel.org/stable/c/81dd117c04422c6d0c7974aba9fa6a0ba370959b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f8495d67434e1cb7e511297687ca55fdb28e4c20","name":"https://git.kernel.org/stable/c/f8495d67434e1cb7e511297687ca55fdb28e4c20","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2e2f130951d34871b0643bf700164d97cff4b427","name":"https://git.kernel.org/stable/c/2e2f130951d34871b0643bf700164d97cff4b427","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1853f30cf5c84971f99788a76207c6f745380896","name":"https://git.kernel.org/stable/c/1853f30cf5c84971f99788a76207c6f745380896","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-97959","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97959","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1e052be69d045c8d0f82ff1116fd3e5a79661745 2e2f130951d34871b0643bf700164d97cff4b427 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1e052be69d045c8d0f82ff1116fd3e5a79661745 f8495d67434e1cb7e511297687ca55fdb28e4c20 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1e052be69d045c8d0f82ff1116fd3e5a79661745 81dd117c04422c6d0c7974aba9fa6a0ba370959b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1e052be69d045c8d0f82ff1116fd3e5a79661745 1853f30cf5c84971f99788a76207c6f745380896 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.1","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.1 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.111 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.53 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.7 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/sched/cls_route.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"2e2f130951d34871b0643bf700164d97cff4b427","status":"affected","version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","versionType":"git"},{"lessThan":"f8495d67434e1cb7e511297687ca55fdb28e4c20","status":"affected","version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","versionType":"git"},{"lessThan":"81dd117c04422c6d0c7974aba9fa6a0ba370959b","status":"affected","version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","versionType":"git"},{"lessThan":"1853f30cf5c84971f99788a76207c6f745380896","status":"affected","version":"1e052be69d045c8d0f82ff1116fd3e5a79661745","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/sched/cls_route.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.1"},{"lessThan":"4.1","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.111","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.53","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.7","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.111","versionStartIncluding":"4.1","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.53","versionStartIncluding":"4.1","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.7","versionStartIncluding":"4.1","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc3","versionStartIncluding":"4.1","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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 '"}],"providerMetadata":{"dateUpdated":"2026-09-25T10:23:04.348Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"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"}],"title":"net/sched: cls_route: free emptied bucket on filter move","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-97959","datePublished":"2026-09-25T10:23:04.348Z","dateReserved":"2026-09-25T10:18:58.205Z","dateUpdated":"2026-09-25T10:23:04.348Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-25 11:17:23","lastModifiedDate":"2026-09-25 11:17:23","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"97959","Ordinal":"1","Title":"net/sched: cls_route: free emptied bucket on filter move","CVE":"CVE-2026-97959","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"97959","Ordinal":"1","NoteData":"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 '","Type":"Description","Title":"net/sched: cls_route: free emptied bucket on filter move"}]}}}