Out-of-bounds read in Bluetooth Controller ISOAL framed RX reassembly leaks adjacent memory into host HCI ISO packets

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Summary

CVECVE-2026-9263
StatePUBLISHED
Assignerzephyr
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-30 17:16:26 UTC
Updated2026-07-01 18:31:30 UTC
DescriptionThe 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().

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS: 0.001720000 probability, percentile 0.068270000 (date 2026-07-02)

Problem Types: CWE-125 | CWE-125 bounds

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
3.1CNACVSS6.5MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Zephyrproject Zephyr affected 3.3.0 4.5.0 semver Not specified

References

ReferenceSourceLinkTags
github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6gvp-pmh8-... 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/zephyrproject-rtos/zephyr/commit/28080d80fc8aca30af1dfd1338bd... [email protected] github.com
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