{"id":"CVE-2026-97959","title":"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 han…","summary":"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 han…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 1e052be69d045c8d0f82ff1116fd3e5a79661745 < 2e2f130951d34871b0643bf700164d97cff4b427","Linux >= 1e052be69d045c8d0f82ff1116fd3e5a79661745 < f8495d67434e1cb7e511297687ca55fdb28e4c20","Linux >= 1e052be69d045c8d0f82ff1116fd3e5a79661745 < 81dd117c04422c6d0c7974aba9fa6a0ba370959b","Linux >= 1e052be69d045c8d0f82ff1116fd3e5a79661745 < 1853f30cf5c84971f99788a76207c6f745380896","Linux 4.1"],"published":"2026-09-25","updated":"2026-09-25","sourceUpdated":"2026-09-25T11:17:23.600","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-97959","references":[{"url":"https://git.kernel.org/stable/c/1853f30cf5c84971f99788a76207c6f745380896","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2e2f130951d34871b0643bf700164d97cff4b427","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/81dd117c04422c6d0c7974aba9fa6a0ba370959b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f8495d67434e1cb7e511297687ca55fdb28e4c20","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-25T11:06:38.876Z","slug":"CVE-2026-97959","body":"## Overview\n\nIn 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 '\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}