CVE-2026-99239

Bluetooth: L2CAP: refuse __l2cap_chan_add if chan already has conn

CVSS 3.1 7.8 HIGHCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-99239

Published

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: refuse __l2cap_chan_add if chan already has conn l2cap_chan may be linked to l2cap_conn at most once. This is assumed in several places, eg l2cap_chan_del cleanup. There is a TOCTOU race where the invariant is violated: [Task 1] [Task 2] l2cap_chan_connect l2cap_sock_bind l2cap_chan_lock lock_sock l2cap_state_change if (sk->sk_state != BT_OPEN) chan->state = BT_CONNECT l2cap_sock_state_change_cb chan->state = BT_BOUND sk->sk_state = BT_BOUND lock_sock <------------------ release_sock sk->sk_state = BT_CONNECT l2cap_sock_connect() does not check sk->sk_state, so since chan->state is now BT_BOUND, subsequent connect() ends up with second __l2cap_chan_add. Explicitly document and check the invariant in __l2cap_chan_add with WARN_ON_ONCE. The only callsite where it could be hit is l2cap_chan_connect, so add pre-check there to avoid relying on chan->state. chan->state read/write is not properly guarded currently so there can be other TOCTOUC problems. Add l2cap_lock_chan in l2cap_sock_bind() to guard chan->state write.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-99239

Published

Linux

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/bluetooth/l2cap_core.c",
                        "net/bluetooth/l2cap_sock.c"
                    ],
                    "versions": [
                        {
                            "version": "8f90405a4a6f1f1880dc07996b47bf57c712bd8a",
                            "lessThan": "85cc289eb08afa975375f838187369e68b429ee0",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "32d783cafb46ff3ca58e6f9fd62c9c5f35eaf26b",
                            "lessThan": "820579652b24ce277e0097cd65b42bd9b7b8bf07",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "8922c7940bae9ce4b1736dddb6362370793835c2",
                            "lessThan": "e618d928ec7f88cbeadfa3542adcac40f474e629",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "91047a4396a8b1857a6f712a90cf33ec0012b189",
                            "lessThan": "fabaff1c59ff2cc89cb7e5bd0186a5e15f0c73b2",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "0b0e2bf39cf99e458d991b9df253727e036a7d7d",
                            "lessThan": "52fe88e4ef87311eee32b45c65603e7c69e75e7d",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "d3b739db5dc6f688a60d56da872fabaf65246032",
                            "lessThan": "10c705dd706aa93164ba41f2566f15206d6c178e",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "b66774b48dd98f07254951f74ea6f513efe7ff8b",
                            "lessThan": "73820561d8cbfd3364a29b8fa77f1707f26029da",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "b66774b48dd98f07254951f74ea6f513efe7ff8b",
                            "lessThan": "d3afd7803f9bc2a8c4270199497b60158b2fc647",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "b66774b48dd98f07254951f74ea6f513efe7ff8b",
                            "lessThan": "86b55991d3cd690e73c5ef8d20b75ae4905b357a",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "50c38d9f42a529691e4e67ea9cedf4f0bfc8d277",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "5.10.265",
                            "lessThan": "5.10.273",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.15.216",
                            "lessThan": "5.15.224",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.1.183",
                            "lessThan": "6.1.191",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.145",
                            "lessThan": "6.6.161",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.97",
                            "lessThan": "6.12.115",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.39",
                            "lessThan": "6.18.60",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.1.4",
                            "lessThan": "7.2",
                            "status": "affected",
                            "versionType": "semver"
                        }
                    ]
                }

Linux

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/bluetooth/l2cap_core.c",
                        "net/bluetooth/l2cap_sock.c"
                    ],
                    "versions": [
                        {
                            "version": "7.2",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "7.2",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.10.273",
                            "lessThanOrEqual": "5.10.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.15.224",
                            "lessThanOrEqual": "5.15.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.1.191",
                            "lessThanOrEqual": "6.1.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.161",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.115",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.60",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2.14",
                            "lessThanOrEqual": "7.2.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.3.1",
                            "lessThanOrEqual": "7.3.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.4-rc1",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON