Zephyr Project up to 4.4.x Bluetooth Host hfp_hf.c bt_hfp_hf_connect null pointer dereference

Summaryinfo

A vulnerability was found in Zephyr Project Zephyr up to 4.4.x. It has been classified as critical. This issue affects the function bt_hfp_hf_connect of the file subsys/bluetooth/host/classic/hfp_hf.c of the component Bluetooth Host. This manipulation causes null pointer dereference. The identification of this vulnerability is CVE-2026-82388. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical was found in Zephyr Project Zephyr up to 4.4.x. Affected by this vulnerability is the function bt_hfp_hf_connect of the file subsys/bluetooth/host/classic/hfp_hf.c of the component Bluetooth Host. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. The summary by CVE is:

bt_hfp_hf_connect() in subsys/bluetooth/host/classic/hfp_hf.c allocates the per-connection HFP Hands-Free object with hfp_hf_create(), which starts an SDP discovery by passing the object's embedded hf->sdp_param to bt_sdp_discover(). That call links the caller-owned parameter block into the SDP client's request list (session->reqs in subsys/bluetooth/host/classic/sdp.c). If the subsequent bt_rfcomm_dlc_connect() then failed, the affected code wiped the entire object with (void)memset(new_hf, 0, sizeof(*new_hf)) while that discovery was still outstanding, zeroing the sys_snode_t _node that is still linked in the SDP client's list along with the request's func, uuid and pool pointers, and zeroing the hf->slc_work work item that may already be queued on the system workqueue. The discovery could not be retracted instead: bt_sdp_discover_cancel() is declared in include/zephyr/bluetooth/classic/sdp.h but has no implementation. The failing branch is reachable with peer-supplied input. The documented use of bt_hfp_hf_connect() is to pass the RFCOMM channel read out of the remote Audio Gateway's SDP record; neither bt_sdp_get_proto_param() nor bt_hfp_hf_connect() range-checks that value, so a remote device advertising an HFP AG record with an RFCOMM channel outside 1-30 makes bt_rfcomm_dlc_connect() return -EINVAL and drives the local device into the wipe. The same branch is reached without any application misuse when the remote peer controls connection timing, for example when the RFCOMM session is in BT_RFCOMM_STATE_DISCONNECTING or the ACL is dropped between object creation and the RFCOMM call. Once the object has been wiped, the Bluetooth host continues to use it: sdp_client_alloc_buf() dereferences session->param->pool, which is now NULL, and the SDP receive paths call session->param->func() through a null function pointer, neither of which is NULL-checked. Because the wipe also clears hf->acl, the pool slot is considered free and a retry or an incoming HFP connection re-appends the same still-linked list node, turning session->reqs into a self-referential list that the host's list walkers never leave. The result is a fault or an unrecoverable hang in the Bluetooth host thread; the stray indirect call is through an all-zero pointer whose target the attacker does not control, so the practical impact is denial of service. The fix keeps the object allocated and marks it with a new BT_HFP_HF_FLAG_RELEASING flag, letting bt_hfp_hf_discover_cb() release it once the discovery completes instead of destroying it under the SDP client. Only builds with CONFIG_BT_CLASSIC and CONFIG_BT_HFP_HF enabled are affected.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-82388 since 08/28/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available.

Upgrading to version 4.5.0 eliminates this vulnerability.

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Productinfo

Type

• Project Management Software

Vendor

• Zephyr Project

Name

• Zephyr

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4

CPE 2.3info

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CPE 2.2info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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