Bluetooth Classic AVRCP Target: missing TX cleanup on disconnect permanently stalls vendor-dependent responses and leaks them to the next peer
Summary
| CVE | CVE-2026-85033 |
|---|---|
| State | PUBLISHED |
| Assigner | zephyr |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-11-03 14:17:38 UTC |
| Updated | 2026-11-03 19:18:11 UTC |
| Description | The AVRCP Target role in subsys/bluetooth/host/classic/avrcp.c keeps its vendor-dependent response transmit state in a per-connection object selected by connection index (get_avrcp_tg()), with the per-transfer context (tid, sent_len, and the BT_AVRCP_TG_FLAG_TX_ONGOING flag) stored in the user_data of the queued response net_buf. The AVCTP teardown handler avrcp_disconnected() did not cancel tg->vd_rsp_tx_work and did not release the buffers still queued on tg->vd_rsp_tx_pending, so a link drop in the middle of a fragmented response left the buffer on the list with TX_ONGOING still set. A remote AVRCP Controller can trigger this deterministically: it issues a vendor-dependent command whose response exceeds one AVRCP fragment (for example GetElementAttributes or GetCapabilities), lets bt_avrcp_tg_vendor_tx_work() emit the START fragment, and then drops the ACL link instead of sending REQUEST_CONTINUING_RESPONSE. The AVCTP control channel requires an encrypted BR/EDR link (BT_SECURITY_L2), so the attacker must be a paired peer within radio range; no user interaction is needed. Because the Target objects are static and reused, the next connection landing on the same connection index finds the stale buffer at the head of vd_rsp_tx_pending. Every run of the TX work sees TX_ONGOING and returns immediately, so all further vendor-dependent responses queue behind the stale head and are never sent — a persistent loss of AVRCP Target function that no timeout clears and only a reboot recovers. Each cycle also leaks one response buffer from a shallow application pool, and a new peer that sends REQUEST_CONTINUING_RESPONSE clears the stale TX_ONGOING via bt_avrcp_tg_process_continuing_cmd(), causing the un-sent remainder of the previous peer's response to be transmitted to it. The fix cancels tg->vd_rsp_tx_work and unrefs every buffer on tg->vd_rsp_tx_pending in avrcp_disconnected(); since the TX context lives in the buffer user_data, releasing the buffers also resets the TX state machine. There is no memory corruption: the pre-fix buffer is leaked with a live reference, so no use-after-free arises. |
Risk And Classification
Primary CVSS: v3.1 4.6 MEDIUM from [email protected]
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L
Problem Types: CWE-459 | CWE-459 dos
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 4.6 | MEDIUM | CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L |
| 3.1 | CNA | CVSS | 4.6 | MEDIUM | CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L |
CVSS v3.1 Breakdown
Attack Vector
AdjacentAttack Complexity
LowPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
LowIntegrity
NoneAvailability
LowCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Zephyrproject | Zephyr | affected 4.4.0 4.5.0 semver | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-2fqc-xhj4-... | [email protected] | github.com | |
| github.com/zephyrproject-rtos/zephyr/commit/47728746bb52863607f06072c13a... | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.