CVE-2026-90091 (GCVE-0-2026-90091)
Vulnerability from cvelistv5
Published
2026-09-17 16:06
Modified
2026-10-19 08:57
Severity ?
8.0 (High) - CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs. put_chan For L2CAP sockets without owning sk->sk_socket, reading l2cap_pi(sk)->chan may race against concurrent l2cap_sock_kill() -> l2cap_sock_put_chan(). This excludes simultaneous proto_ops callbacks, but access in l2cap_sock_cleanup_listen() has unsafe lockless read. [Task 1] [Task 2 (hdev->workqueue)] l2cap_sock_release(parent) l2cap_disconn_cfm l2cap_sock_cleanup_listen l2cap_conn_del bt_accept_dequeue l2cap_chan_del lock_sock(sk) l2cap_sock_teardown_cb bt_accept_unlink bt_sk(sk)->parent = NULL release_sock(sk) ----------------> lock_sock(sk) parent = /* NULL */ lock_sock(sk) <--------------------- release_sock(sk) sock_set_flag(sk, SOCK_ZAPPED) l2cap_sock_close_cb l2cap_sock_kill(sk) l2cap_sock_put_chan chan = READ l2cap_pi(sk)->chan l2cap_pi(sk)->chan = NULL l2cap_chan_hold_unless_zero l2cap_put_chan(chan) kref_get_unless_zero(&chan->ref) Task 1 may observe NULL which causes null-ptr-deref. Fix the race by taking lock_sock() in l2cap_sock_kill() to synchronize with l2cap_sock_cleanup_listen(). hold_unless_zero() is not needed here, l2cap_pi(sk)->chan owns reference if it is non-NULL. Clarify code comments vs. locking.
References
Impacted products
Vendor Product Version
Linux Linux Version: b39298044e5534612511a2ff5de03ba5f6e7a820
Version: 8c37e4338c801ebb8cee52436c01c41e009f6e87
Version: 84e718b6a814edc84159361f9f454a4e92ae91ae
Version: 36da806f7fbaee56ad9e81859deec203f9728700
Version: 6fef032af0092ed5ccb767239a9ac1bc38c08a40
Version: 6fef032af0092ed5ccb767239a9ac1bc38c08a40
Version: 733e76e74e406c1d1ddc7369420dd8a47f48bb8a
Version: 6.1.178   ≤
Version: 6.6.145   ≤
Version: 6.12.97   ≤
Version: 6.18.40   ≤
Version: 7.1.5   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/bluetooth/l2cap.h",
            "net/bluetooth/l2cap_sock.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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              "status": "affected",
              "version": "7.1.5",
              "versionType": "semver"
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          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/net/bluetooth/l2cap.h",
            "net/bluetooth/l2cap_sock.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.2"
            },
            {
              "lessThan": "7.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.110",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
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            },
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              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                },
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                  "versionStartIncluding": "6.6.145",
                  "vulnerable": true
                },
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.110",
                  "versionStartIncluding": "6.12.97",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.52",
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                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
                  "versionStartIncluding": "7.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.2",
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                },
                {
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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-\u003esk_socket, reading\nl2cap_pi(sk)-\u003echan may race against concurrent l2cap_sock_kill() -\u003e\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-\u003eworkqueue)]\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)-\u003eparent = NULL\n       release_sock(sk) ----------------\u003e lock_sock(sk)\n                                          parent = /* NULL */\n     lock_sock(sk) \u003c--------------------- 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)-\u003echan         l2cap_pi(sk)-\u003echan = NULL\n     l2cap_chan_hold_unless_zero            l2cap_put_chan(chan)\n       kref_get_unless_zero(\u0026chan-\u003eref)\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)-\u003echan owns reference if it is non-NULL.\n\nClarify code comments vs. locking."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:A - A nearby peer\u0027s HCI Disconnection Complete (hci_disconn_complete_evt \u2192 hci_disconn_cfm \u2192 l2cap_disconn_cfm on hdev-\u003erx_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 \u2192 l2cap_sock_cleanup_listen \u2192 bt_accept_dequeue, while the peer\u0027s disconnect concurrently runs l2cap_sock_kill \u2192 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 \u003e= 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)-\u003echan of the unaccepted child; it does not escape a VM, bypass an IOMMU, or leave the kernel\u0027s own authority.\nC:H - cleanup_listen loads l2cap_pi(sk)-\u003echan then calls l2cap_chan_hold_unless_zero(); concurrent l2cap_sock_put_chan plus l2cap_conn_del\u0027s 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-\u003eops 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(\u0026c-\u003ekref) with c==NULL and oopses; the UAF interleaving likewise panics on poisoned slab or a corrupted chan mutex."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:57:49.423Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90091",
    "datePublished": "2026-09-17T16:06:05.478Z",
    "dateReserved": "2026-09-11T19:38:34.786Z",
    "dateUpdated": "2026-10-19T08:57:49.423Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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