Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
zephyrproject zephyr — Out-of-bounds read in Bluetooth Controller ISOAL framed RX reassembly leaks adjacent memory into host HCI ISO packets
AV AC PR UI S C I A CVSS EPSS %ile KEV
A L N N U H N H 8.1 .0031 24.1 —
AFFECTED
Product Versions Fixed
zephyr 3.3.0 – —
TIMELINE
May 21 Reserved by zephyr
Jun 30 EXPLOIT PUBLISHED — CVE-2026-9263 (zephyrproject zephyr). Public exploit reference added.
Jun 30 Published (CNA: zephyr)
Description
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. 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().
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
|---|
| May 21, 2026 | Reserved | Reserved by zephyr |
| June 30, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-9263 (zephyrproject zephyr). Public exploit reference added. |
| June 30, 2026 | Published | Published (CNA: zephyr) |
Affected
Affected products and packages — 1 row
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| zephyrproject | zephyr | — | 3.3.0 | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-9263 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.