{"id":"CVE-2026-99239","published":"2026-11-02T16:17:49.540","lastModified":"2026-11-02T16:17:49.540","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: refuse __l2cap_chan_add if chan already has conn\n\nl2cap_chan may be linked to l2cap_conn at most once. This is assumed in\nseveral places, eg l2cap_chan_del cleanup.\n\nThere is a TOCTOU race where the invariant is violated:\n\n    [Task 1]                          [Task 2]\n    l2cap_chan_connect                l2cap_sock_bind\n      l2cap_chan_lock                   lock_sock\n      l2cap_state_change                if (sk->sk_state != BT_OPEN)\n        chan->state = BT_CONNECT\n        l2cap_sock_state_change_cb      chan->state = BT_BOUND\n                                        sk->sk_state = BT_BOUND\n          lock_sock <------------------ release_sock\n          sk->sk_state = BT_CONNECT\n\nl2cap_sock_connect() does not check sk->sk_state, so since chan->state\nis now BT_BOUND, subsequent connect() ends up with second\n__l2cap_chan_add.\n\nExplicitly document and check the invariant in __l2cap_chan_add with\nWARN_ON_ONCE. The only callsite where it could be hit is\nl2cap_chan_connect, so add pre-check there to avoid relying on\nchan->state. chan->state read/write is not properly guarded currently so\nthere can be other TOCTOUC problems.\n\nAdd l2cap_lock_chan in l2cap_sock_bind() to guard chan->state write.","cvssScore":7.8,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/10c705dd706aa93164ba41f2566f15206d6c178e","tags":[]},{"url":"https://git.kernel.org/stable/c/52fe88e4ef87311eee32b45c65603e7c69e75e7d","tags":[]},{"url":"https://git.kernel.org/stable/c/73820561d8cbfd3364a29b8fa77f1707f26029da","tags":[]},{"url":"https://git.kernel.org/stable/c/820579652b24ce277e0097cd65b42bd9b7b8bf07","tags":[]},{"url":"https://git.kernel.org/stable/c/85cc289eb08afa975375f838187369e68b429ee0","tags":[]},{"url":"https://git.kernel.org/stable/c/d3afd7803f9bc2a8c4270199497b60158b2fc647","tags":[]},{"url":"https://git.kernel.org/stable/c/e618d928ec7f88cbeadfa3542adcac40f474e629","tags":[]},{"url":"https://git.kernel.org/stable/c/fabaff1c59ff2cc89cb7e5bd0186a5e15f0c73b2","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}