{"cve":"CVE-2026-90248","nvd":{"published":"2026-09-17T17:17:20.947","modified":"2026-10-19T09:19:15.323","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_api: fix teardown of an adopted proto on insert-race loss\n\nIn tc_new_tfilter() the create branch sets tp_created = 1 before calling\ntcf_chain_tp_insert_unique(). When the caller loses the race (another\nrequest inserted a proto at the same chain/prio first), insert_unique()\ndestroys the caller's own tp_new and returns the winner's proto with an\nextra reference. tp_created was never cleared, so the loser's errout\npath treated the winner's live proto as its own and called\ntcf_chain_tp_delete_empty() on it, silently unlinking an active\nclassifier that the winning request already advertised via\nRTM_NEWTFILTER.\n\nTrack the outcome of the insert step in a single tri-state variable so\neach errout path reacts correctly:\n\n- TP_NOT_CREATED: no proto created; pursue the old path.\n- TP_CREATED: proto inserted successfully; same code path as before.\n- TP_NOT_OWNED: New - lost the insert race; tp is another request's proto\n  (chain ref already released by tp_new's destroy)\n\nBoth errout reactions are single expressions derived from the state.\n\nThis fix is motivated by the Sashiko's automated review of Patch\n(net/sched: cls_api: Always acquire rtnl_lock when destroying locked\nclassifiers) [1][2]. The review identified the silent-unlink behaviour of\nan adopted proto's teardown when a request loses the\ntcf_chain_tp_insert_unique() race.\n\n[1] https://sashiko.dev/#/patchset/20260801125632.360365-1-jhs%40mojatatu.com\n[2] https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260801125632.360365-1-jhs%40mojatatu.com","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/219c87aeefdcc8c1caf28cc99e9b361ce7393d3a","https://git.kernel.org/stable/c/a68e664ddf16ecae6d769d6a2eb356f8abab75c9","https://git.kernel.org/stable/c/bbe2fd6d77df630356185406a97317f6aa6a92cf","https://git.kernel.org/stable/c/bee2208276c8e0e40a249ffdcf6e5434a79a847c","https://git.kernel.org/stable/c/d4e359b3608a0e184bbe8d61a5c3b50d0831c44a"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:55:23.253742848+00:00"},"epss":{"cve":"CVE-2026-90248","score":0.00211,"percentile":0.11295,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}