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CVE-2026-9263

Status: AnalyzedHigh (8.1)—

The Zephyr Bluetooth controller ISO Adaptation Layer (subsys/bluetooth/controller/ll_sw/isoal.c) fails to validate the length field of a framed ISO PDU start segment. Per the Bluetooth specification a start segment (sc=0) always carries a 3-byte time_offset, so its segment-header len must be at least PDU_ISO_SEG_TIMEOFFSET_SIZE (3). isoal_check_seg_header() accepted start segments with len < 3 as valid, and isoal_rx_framed_consume() then computed length = seg_hdr->len - 3 in a uint8_t, underflowing to 253-255 when len is 0-2.

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That oversized length is passed to isoal_rx_append_to_sdu(), whose copy is clamped only against the destination SDU buffer size, not the source PDU length, so up to ~255 bytes of controller memory beyond the received PDU are copied (via sink_sdu_write_hci()/net_buf_add_mem) into an HCI ISO data packet and delivered to the host. The PDU and its segment headers are entirely attacker-controlled and arrive over the air, reachable through both the CIS and BIS-sync HCI data paths (hci_driver.c) and the vendor data path (ull_iso.c), so a remote CIS peer or a broadcaster the device is synced to can trigger an out-of-bounds read causing information disclosure to the host and potential denial of service (faults or malformed oversized HCI ISO packets). The flaw affects all Zephyr releases since framed ISO reception was introduced in v3.0.0. The fix rejects sc=0 segments with len < 3 in isoal_check_seg_header() and adds a guard before the subtraction in isoal_rx_framed_consume().

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

AV:A (red adyacente) sin privilegios → T1210. La lectura out-of-bounds de memoria del controlador Bluetooth descifra datos sensibles (C:H) → T1005. El desbordamiento puede causar fallos o DoS en la capa de HCI → T1499.004.

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Vulnerability ScanningThreat Intelligence ProgramPrivileged Account ManagementNetwork SegmentationFilter Network TrafficDisable or Remove Feature or Program

Affected technologies (1)

Zephyrproject — Zephyr

CWEs

References

Raw JSON (NVD)

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