RFCOMM session-disconnect race leaks session/L2CAP and denies further RFCOMM service in Zephyr Bluetooth Classic

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Summary

CVECVE-2026-10654
StatePUBLISHED
Assignerzephyr
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-30 17:16:20 UTC
Updated2026-07-01 18:31:30 UTC
DescriptionA race condition in the Zephyr Bluetooth Classic RFCOMM host stack (subsys/bluetooth/host/classic/rfcomm.c) mishandles a simultaneous bidirectional session disconnect. When the local device has initiated a session teardown (state BT_RFCOMM_STATE_DISCONNECTING, DISC sent, RTX timer armed) and the connected peer concurrently sends its own DISC frame for dlci 0, rfcomm_handle_disc() invokes rfcomm_session_disconnected(), which unconditionally forced the session to BT_RFCOMM_STATE_DISCONNECTED without ever calling bt_l2cap_chan_disconnect(). Because the recovery timer was also cancelled and a later UA is ignored in the DISCONNECTED state, the session becomes permanently wedged: the underlying L2CAP channel is never released and the session slot in the fixed bt_rfcomm_pool[CONFIG_BT_MAX_CONN] array is never reclaimed (its conn pointer stays set). Subsequent bt_rfcomm_dlc_connect() calls on that connection fail with -EINVAL due to the invalid session state, so RFCOMM service is denied for that peer, and repeated occurrences can exhaust the session pool. The DISC frame is peer-controlled over the air, but exploitation requires the peer's DISC to collide with a local-initiated disconnect (a high-complexity timing race). Impact is availability/resource-leak only; there is no memory-safety, confidentiality, or integrity consequence. The defect shipped in released versions (present in v4.4.0 and earlier). The fix only transitions to DISCONNECTED when the session is not already in DISCONNECTING, preserving the proper L2CAP teardown path.

Risk And Classification

Primary CVSS: v3.1 3.1 LOW from [email protected]

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS: 0.001240000 probability, percentile 0.024750000 (date 2026-07-03)

Problem Types: CWE-362 | CWE-362 race

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.1LOWCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNACVSS3.1LOWCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Zephyrproject Zephyr affected 1.6.0 4.5.0 semver Not specified

References

ReferenceSourceLinkTags
github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-4m37-wp5x-... [email protected] github.com
github.com/zephyrproject-rtos/zephyr/commit/c67b59f891a3a8697f1edb2a0e55... [email protected] github.com
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