{"schemaVersion":3,"id":"CVE-2026-19939","aliases":[],"status":"published","duplicateOf":null,"title":null,"description":"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.\n\nA 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.\n\nWith 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.\n\nThe 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.","dates":{"published":"2026-10-13T16:39:16.681Z","modified":"2026-10-14T18:49:17.902Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":6.3,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":6.3,"severity":"medium","vector":"CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":6.3,"severity":"medium","vector":"CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00179,"percentile":0.07022,"severity":"low","asOf":"2026-10-19T00:00:00.000Z","change":{"pp":null,"baselineDate":null,"baselineScore":null},"history":[{"date":"2026-10-14T00:00:00.000Z","score":0.00179,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00179,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00179,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00179,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00179,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00179,"percentile":0.07022}],"last30":[{"date":"2026-10-14T00:00:00.000Z","score":0.00179,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00179,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00179,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00179,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00179,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00179,"percentile":0.07022}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-825","name":"Expired Pointer Dereference","description":"The product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid.","type":"weakness","status":"Incomplete","abstraction":"Base","likelihoodOfExploit":null,"url":"https://cwe.mitre.org/data/definitions/825.html"}],"affected":[{"vendor":"zephyrproject","product":"zephyr","name":"zephyr","label":"zephyr","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"≥ 3.7.0, ≤ 4.4.2","noFixRecorded":false,"fixedIn":null}],"versionsText":"≥ 3.7.0, ≤ 4.4.2","eol":null,"hubHref":"/vendor/zephyrproject/zephyr"}],"affectedCount":1,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/a10d18c3be9d1a968574dbfbce6baee58ea398e8","label":"github.com/zephyrproject-rtos/zephyr/commit/a10d18c3be9d1a968574dbfbce6baee58ea398e8","hostname":"github.com","tags":["Patch"]},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-9mww-f3h4-mq95","label":"github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-9mww-f3h4-mq95","hostname":"github.com","tags":[]}],"lineage":{"upstream":[],"downstream":[],"duplicates":[],"related":[]},"timeline":[{"kind":"published","date":"2026-10-13T16:39:16.681Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-10-14T18:49:17.902Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":25,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-20T04:49:24.760Z","stale":false,"partial":false}}