{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-90091", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.786Z", "datePublished": "2026-09-17T16:06:05.478Z", "dateUpdated": "2026-10-19T08:57:49.423Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:57:49.423Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs. put_chan\n\nFor L2CAP sockets without owning sk->sk_socket, reading\nl2cap_pi(sk)->chan may race against concurrent l2cap_sock_kill() ->\nl2cap_sock_put_chan(). This excludes simultaneous proto_ops callbacks,\nbut access in l2cap_sock_cleanup_listen() has unsafe lockless read.\n\n [Task 1] [Task 2 (hdev->workqueue)]\n l2cap_sock_release(parent) l2cap_disconn_cfm\n l2cap_sock_cleanup_listen l2cap_conn_del\n bt_accept_dequeue l2cap_chan_del\n lock_sock(sk) l2cap_sock_teardown_cb\n bt_accept_unlink\n bt_sk(sk)->parent = NULL\n release_sock(sk) ----------------> lock_sock(sk)\n parent = /* NULL */\n lock_sock(sk) <--------------------- release_sock(sk)\n sock_set_flag(sk, SOCK_ZAPPED)\n l2cap_sock_close_cb\n l2cap_sock_kill(sk)\n l2cap_sock_put_chan\n chan = READ l2cap_pi(sk)->chan l2cap_pi(sk)->chan = NULL\n l2cap_chan_hold_unless_zero l2cap_put_chan(chan)\n kref_get_unless_zero(&chan->ref)\n\nTask 1 may observe NULL which causes null-ptr-deref.\n\nFix the race by taking lock_sock() in l2cap_sock_kill() to\nsynchronize with l2cap_sock_cleanup_listen(). hold_unless_zero() is not\nneeded here, l2cap_pi(sk)->chan owns reference if it is non-NULL.\n\nClarify code comments vs. locking." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:A - A nearby peer's HCI Disconnection Complete (hci_disconn_complete_evt → hci_disconn_cfm → l2cap_disconn_cfm on hdev->rx_work) or L2CAP_DISCONN_REQ (l2cap_disconnect_req) runs l2cap_sock_put_chan on an unaccepted child created by L2CAP_CONN_REQ; the transport is Bluetooth radio range, so Adjacent not Network.\nAC:L - The attacker drives both sides: close() of their listening socket runs l2cap_sock_release → l2cap_sock_cleanup_listen → bt_accept_dequeue, while the peer's disconnect concurrently runs l2cap_sock_kill → l2cap_sock_put_chan on that child without lock_sock; repeating connect/disconnect/close hits the window.\nPR:L - l2cap_sock_create() allows unprivileged SOCK_SEQPACKET/SOCK_STREAM (only SOCK_RAW needs CAP_NET_RAW), and l2cap_validate_bredr_psm() permits dynamic PSM >= 0x1001 without CAP_NET_BIND_SERVICE, so listen()+close() needs only a normal local account; AF_BLUETOOTH is init_net-only (bt_sock_create), not a userns CAP_NET_ADMIN path.\nUI:N - The attacker closes their own listening L2CAP socket and, from a radio they control, sends L2CAP_CONN_REQ then disconnect; no other user must pair, accept, or confirm during the race.\nS:U - The race corrupts the host kernel l2cap_chan stored in l2cap_pi(sk)->chan of the unaccepted child; it does not escape a VM, bypass an IOMMU, or leave the kernel's own authority.\nC:H - cleanup_listen loads l2cap_pi(sk)->chan then calls l2cap_chan_hold_unless_zero(); concurrent l2cap_sock_put_chan plus l2cap_conn_del's final l2cap_chan_put can kfree that object first, so kref_get_unless_zero and later l2cap_chan_lock/__set_chan_timer run on a freed kmalloc l2cap_chan that can be sprayed for disclosure.\nI:H - Winning that UAF lets cleanup_listen take l2cap_chan_lock, arm __set_chan_timer, and l2cap_chan_put on a reclaimed fake chan, corrupting mutex/timer/kref state and invoking chan->ops from sprayed memory for hijack.\nA:H - If cleanup_listen observes the NULL stored by l2cap_sock_put_chan, l2cap_chan_hold_unless_zero() calls kref_get_unless_zero(&c->kref) with c==NULL and oopses; the UAF interleaving likewise panics on poisoned slab or a corrupted chan mutex." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/bluetooth/l2cap.h", "net/bluetooth/l2cap_sock.c" ], "versions": [ { "version": "b39298044e5534612511a2ff5de03ba5f6e7a820", "lessThan": "827de6bd2865b22aaabd554540def3b8a33018ab", "status": "affected", "versionType": "git" }, { "version": "8c37e4338c801ebb8cee52436c01c41e009f6e87", "lessThan": "7c7ac736b50fa259ed1bdddc18d79523f07c0442", "status": "affected", "versionType": "git" }, { "version": "84e718b6a814edc84159361f9f454a4e92ae91ae", "lessThan": "4f8c63fe0097c9f6ea34409f82f79b3894903d91", "status": "affected", "versionType": "git" }, { "version": "36da806f7fbaee56ad9e81859deec203f9728700", "lessThan": "61d5ddbd524c715b224cbe7e9f01da4e05098b19", "status": "affected", "versionType": "git" }, { "version": "6fef032af0092ed5ccb767239a9ac1bc38c08a40", "lessThan": "32a7bc6e93be36b37fe61f351d312d358195bd61", "status": "affected", "versionType": "git" }, { "version": "6fef032af0092ed5ccb767239a9ac1bc38c08a40", "lessThan": "66d6ef18548ae6d7dd452b84115fc82c0a73a4ea", "status": "affected", "versionType": "git" }, { "version": "733e76e74e406c1d1ddc7369420dd8a47f48bb8a", "status": "affected", "versionType": "git" }, { "version": "6.1.178", "lessThan": "6.1.188", "status": "affected", "versionType": "semver" }, { "version": "6.6.145", "lessThan": "6.6.157", "status": "affected", "versionType": "semver" }, { "version": "6.12.97", "lessThan": "6.12.110", "status": "affected", "versionType": "semver" }, { "version": "6.18.40", "lessThan": "6.18.52", "status": "affected", "versionType": "semver" }, { "version": "7.1.5", "lessThan": "7.2", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/bluetooth/l2cap.h", "net/bluetooth/l2cap_sock.c" ], "versions": [ { "version": "7.2", "status": "affected" }, { "version": "0", "lessThan": "7.2", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.110", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.52", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.6", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.178", "versionEndExcluding": "6.1.188" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.145", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.97", "versionEndExcluding": "6.12.110" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18.40", "versionEndExcluding": "6.18.52" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.2", "versionEndExcluding": "7.2.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.2", "versionEndExcluding": "7.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.1.5" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/827de6bd2865b22aaabd554540def3b8a33018ab" }, { "url": "https://git.kernel.org/stable/c/7c7ac736b50fa259ed1bdddc18d79523f07c0442" }, { "url": "https://git.kernel.org/stable/c/4f8c63fe0097c9f6ea34409f82f79b3894903d91" }, { "url": "https://git.kernel.org/stable/c/61d5ddbd524c715b224cbe7e9f01da4e05098b19" }, { "url": "https://git.kernel.org/stable/c/32a7bc6e93be36b37fe61f351d312d358195bd61" }, { "url": "https://git.kernel.org/stable/c/66d6ef18548ae6d7dd452b84115fc82c0a73a4ea" } ], "title": "Bluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs. put_chan", "x_generator": { "engine": "bippy-1.2.0" } } } }