CVE-2026-82388 — Use of a released HFP HF object after a failed RFCOMM connect in the Bluetooth Classic host
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.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.2% (30-day exploitation probability)+2
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Zephyrproject Zephyr).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Zephyrproject | Zephyr | ≥ 4.4.0 and < 4.5.0 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 5.3 | CVSS 3.1 | Medium | 1.6 | 3.6 | vulnerabilities@zephyrproject.org via NIST National Vulnerability Database |
| 5.3 | CVSS 3.1 | Medium | — | — | zephyr via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: vulnerabilities@zephyrproject.org) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 27, 2026 → Oct 29, 2026 · 3 reading(s) · max 0.21%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- Source status changed · Received → Awaiting Analysis
- Affected products added · zephyrproject/zephyr
- SSVC assessment updated
- Record published
- CVSS changed · 5.3
- Source status changed · → Received
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× References added · Oct 26, 2026 – Oct 26, 2026
- 1× Official description updated · Oct 26, 2026 – Oct 26, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- High CVE-2026-82961 Unvalidated pin index in GPIO syscall handlers allows out-of-bounds kernel writes from user mode 2d
- Medium CVE-2026-82962 Out-of-bounds write in Zephyr Ethernet L2 when adding the link-layer header to a forwarded packet 2d
- Medium CVE-2026-82389 Bluetooth Classic HFP AG wipes an object still linked in the SDP request list on connect failure, causing a NULL dereference 4d
- High CVE-2026-81038 Bluetooth OTS server discloses uninitialized stack memory in failed Calculate Checksum responses 4d
- Medium CVE-2026-81039 Bluetooth Host connection reservation leak when multiple connectable advertising sets share an identity 4d
- Low CVE-2026-82390 Cross-session AES key confusion in the Espressif ESP32 hardware crypto driver 4d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-82388 is "Use of a released HFP HF object after a failed RFCOMM connect in the Bluetooth Classic host", rated Medium. It affects Zephyr (Zephyrproject); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.3 describes technical severity. EPSS 0.21% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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