CVE-2026-19939

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Source

https://cve.org/CVERecord?id=CVE-2026-19939

Import Source

https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-19939.json

JSON Data

https://api.osv.dev/v1/vulns/CVE-2026-19939

Aliases

GHSA-9mww-f3h4-mq95

Published

2026-10-13T16:39:16Z

Modified

2026-10-28T11:09:34Z

Severity

6.3 (Medium) CVSS_V3 - CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H CVSS Calculator

Summary

Bluetooth Classic AVDTP: stale timeout work on signalling-channel disconnect leads to kernel timeout-list corruption

Details

The AVDTP signalling layer arms a 6-second command timeout (AVDTP_TIMEOUT) in avdtp_send_cmd() whenever the local device issues an AVDTP request. Every response handler in subsys/bluetooth/host/classic/avdtp.c cancels session->timeout_work before clearing the pending request, but bt_avdtp_l2cap_disconnected() only cleared session->req and left the delayable work armed. The struct bt_avdtp session is the first member of struct bt_a2dp, whose instances live in a static per-connection array, and a2dp_get_connection() in subsys/bluetooth/host/classic/a2dp.c wipes a slot with memset() as soon as session->br_chan.chan.conn is NULL — which the L2CAP layer arranges immediately after the disconnect callback returns.

A remote Bluetooth BR/EDR peer triggers the condition by opening the AVDTP signalling channel, letting the local application issue an AVDTP procedure (the standard A2DP flow issues bt_a2dp_discover() from the connected callback), then tearing the signalling channel down without responding and re-opening it within the remaining timeout window. The reconnect reaches a2dp_accept() → a2dp_get_connection(), which zeroes the whole struct bt_a2dp while the work item's struct _timeout is still linked into the kernel's global timeout list. Both the disconnect and the reconnect instants are chosen by the attacker, so no race has to be won; an encrypted BR/EDR link is required, and CONFIG_BT_A2DP (experimental) must be enabled.

With the default CONFIG_TIMEOUT_BACKEND_DLIST backend the kernel decides a timeout is inactive by testing whether its list node is linked, so after the memset() the kernel treats a node that is still on the global timeout list as free: the announce path pops a node whose links and handler pointer are NULL, and the next bt_work_reschedule() on the recycled session re-inserts the same node into a list that already contains it. The consequence is corruption of the single kernel data structure every timer, timeslice and sleep depends on — writes through zeroed or stale list pointers and a NULL handler dispatch — producing a system-wide crash or hang rather than a fault confined to the A2DP session.

The fix cancels session->timeout_work at the top of bt_avdtp_l2cap_disconnected() and moves k_work_init_delayable() from avdtp_send_cmd() to the session-establishment paths bt_avdtp_connect() and bt_avdtp_l2cap_accept(), so the work item is always initialized before a disconnect callback can run.

Database specific

{
    "cna_assigner": "zephyr",
    "cwe_ids": [
        "CWE-825"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/19xxx/CVE-2026-19939.json"
}

References

Affected packages

Git / github.com/zephyrproject-rtos/zephyr

Affected ranges

Type

GIT

Repo

https://github.com/zephyrproject-rtos/zephyr

Events

Introduced

36940db938a8f4a1e919496793ed439850a221c2

Fixed

a10d18c3be9d1a968574dbfbce6baee58ea398e8

Database specific

Show details

{
    "extracted_events": [
        {
            "range": [
                {
                    "introduced": "3.7.0"
                },
                {
                    "last_affected": "4.4.2"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StandardRange"
        },
        {
            "range": [
                {
                    "fixed": "a10d18c3be9d1a968574dbfbce6baee58ea398e8"
                }
            ],
            "source": "REFERENCES_COMMIT"
        }
    ]
}

Affected versions

v3.*

v3.7.0

v4.*

v4.0.0

v4.0.0-rc1

v4.0.0-rc2

v4.0.0-rc3

v4.1.0

v4.1.0-rc1

v4.1.0-rc2

v4.1.0-rc3

v4.2.0

v4.2.0-rc1

v4.2.0-rc2

v4.2.0-rc3

v4.3.0

v4.3.0-rc1

v4.3.0-rc2

v4.3.0-rc3

v4.4.0

v4.4.0-rc1

v4.4.0-rc2

v4.4.0-rc3

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-19939.json"

vanir_signatures

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vanir_signatures_modified

"2026-10-28T11:09:34Z"