CVE-2026-19570 — Out-of-bounds write in LE Audio Broadcast Sink when copying BASE subgroup metadata into the BASS receive state
The LE Audio Broadcast Sink in subsys/bluetooth/audio/bap_broadcast_sink.c copies subgroup metadata from a received Basic Audio Announcement (BASE) into the static Broadcast Audio Scan Service parameter structure mod_src_param without any bounds check. In base_subgroup_meta_cb() the destination element was selected as mod_src_param.subgroups[mod_src_param.num_subgroups] with no test against ARRAY_SIZE(mod_src_param.subgroups) (sized by CONFIG_BT_BAP_BASS_MAX_SUBGROUPS, default 1), and the metadata was copied with memcpy() using the raw on-air length returned by bt_bap_base_get_subgroup_codec_meta() into a metadata array sized by CONFIG_BT_AUDIO_CODEC_CFG_MAX_METADATA_SIZE (default 4). The BASE validator bt_bap_base_get_base_from_ad() only checks structural consistency and permits up to ~24 subgroups and metadata LTVs of ~240 octets. The defect is reached from the periodic advertising receive callback: pa_recv() → bt_data_parse() → pa_decode_base() → update_recv_state_base() → bt_bap_base_foreach_subgroup() → base_subgroup_meta_cb(). Every broadcast sink registers a scan-delegator receive state at creation (bt_bap_broadcast_sink_create() calls broadcast_sink_add_src()), and CONFIG_BT_BAP_BROADCAST_SINK depends on CONFIG_BT_BAP_SCAN_DELEGATOR, so the path is active in every broadcast-sink build once the device is periodic-advertising-synced. An attacker in radio range who operates a broadcast source the device syncs to — or who impersonates the advertiser address and SID of one already in use, periodic advertising data being unauthenticated — can change the BASE at will; each new BASE is re-parsed. A crafted BASE therefore writes attacker-chosen bytes past the end of a fixed static object in .bss: up to roughly 236 bytes for an oversized metadata LTV, plus whole struct bt_bap_bass_subgroup records for each subgroup beyond CONFIG_BT_BAP_BASS_MAX_SUBGROUPS. This is memory corruption of adjacent Bluetooth-audio state reachable with no pairing, bonding or GATT connection, with a potential for remote code execution in the Bluetooth RX thread; in addition, the unvalidated metadata_len is forwarded to bt_bap_scan_delegator_mod_src(), which neither clamps it nor rejects it, leading to a further copy into the receive state and to out-of-bounds memory being disclosed in the BASS receive-state notification sent to a connected Broadcast Assistant. The fix rejects a BASE carrying more subgroups than the receive state can hold (discarding the update entirely) and omits metadata that does not fit rather than copying it, and additionally honours the previously-ignored error return of the subgroup decode pass.
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 0.3% (30-day exploitation probability)+3
- Technical severity (high)+6
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 | ≥ 3.6.0 and ≤ 4.4.2 | 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 |
|---|---|---|---|---|---|
| 8.8 | CVSS 3.1 | High | 2.8 | 5.9 | vulnerabilities@zephyrproject.org via NIST National Vulnerability Database |
| 8.8 | CVSS 3.1 | High | — | — | zephyr via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.29%
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
- Affected products added · zephyrproject/zephyr
- SSVC assessment updated
- Record published
- CVSS changed · 8.8
- Source status changed · → Awaiting Analysis
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-75085 Out-of-bounds read from received-frame length underflow in the STM32WBA IEEE 802.15.4 driver 1d
- Medium CVE-2026-75084 Out-of-bounds write in the TI CC1200 IEEE 802.15.4 driver from an unvalidated radio-supplied packet length 1d
- Medium CVE-2026-75083 Integer underflow of the radio-reported frame length causes an out-of-bounds write in the NXP KW41Z IEEE 802.15.4 driver 1d
- High CVE-2026-19673 Out-of-bounds read and net_buf length underflow in Zephyr Ethernet L2 when parsing a truncated VLAN header 1d
- Medium CVE-2026-19940 Bluetooth HFP AG reuses a connection slot while a delayable work item is still armed, corrupting kernel timeout bookkeeping 2d
- Medium CVE-2026-19939 Bluetooth Classic AVDTP: stale timeout work on signalling-channel disconnect leads to kernel timeout-list corruption 2d
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-2026-19570 is "Out-of-bounds write in LE Audio Broadcast Sink when copying BASE subgroup metadata into the BASS receive state", rated High. It affects Zephyr (Zephyrproject); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.8 describes technical severity. EPSS 0.29% 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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