Description
bt_sdp_parse_attribute() in subsys/bluetooth/host/classic/sdp.c validated only that the SDP record buffer held the type-marker byte plus the 2-byte attribute ID (a check of buf->len < 3) but then read a fourth byte, the data-element descriptor (type), via net_buf_simple_pull_u8(). Because net_buf_simple_pull_u8() dereferences buf->data[0] before its only bounds guard (an __ASSERT_NO_MSG that compiles out when CONFIG_ASSERT is disabled, the production default), a record of exactly three bytes (0x09 followed by a 2-byte attribute ID) causes a one-byte read past the end of the logical buffer. The parser is reachable from inbound, remote-controlled data: a Bluetooth BR/EDR peer acting as an SDP server returns discovery-response records that are stored verbatim in the client receive buffer and parsed via the public bt_sdp_get_attr()/bt_sdp_has_attr()/bt_sdp_record_parse() helpers. The over-read is bounded to a single byte that is used only as an internal length selector and is never leaked to the attacker; subsequent length checks then reject the malformed record. Realistic impact is therefore limited to an edge-case denial of service (a fault only if the record ends exactly at a mapped-memory boundary, or a deterministic assert panic when CONFIG_ASSERT=y). Affects Zephyr v4.3.0 and v4.4.0; fixed by adding sizeof(type) to the length check.
Published: 2026-06-22
Score: 7.1 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
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History

Tue, 14 Jul 2026 19:00:00 +0000

Type Values Removed Values Added
Description A malformed Bluetooth Classic SDP attribute can trigger a reachable assertion in Zephyr's SDP parser. In subsys/bluetooth/host/classic/sdp.c, bt_sdp_parse_attribute() accepts an input buffer once it contains the 1-byte attribute type and 2-byte attribute id, but then unconditionally pulls an additional byte for the value type without verifying that the byte is present. A truncated 3-byte attribute (for example 09 00 09) therefore reaches net_buf_simple_pull() with insufficient remaining length, triggering the __ASSERT_NO_MSG(buf->len >= len) check and a kernel panic in assert-enabled builds (denial of service). In builds where assertions are disabled, parsing may continue past the end of the available buffer, leading to an out-of-bounds read and undefined behavior. bt_sdp_parse_attribute() in subsys/bluetooth/host/classic/sdp.c validated only that the SDP record buffer held the type-marker byte plus the 2-byte attribute ID (a check of buf->len < 3) but then read a fourth byte, the data-element descriptor (type), via net_buf_simple_pull_u8(). Because net_buf_simple_pull_u8() dereferences buf->data[0] before its only bounds guard (an __ASSERT_NO_MSG that compiles out when CONFIG_ASSERT is disabled, the production default), a record of exactly three bytes (0x09 followed by a 2-byte attribute ID) causes a one-byte read past the end of the logical buffer. The parser is reachable from inbound, remote-controlled data: a Bluetooth BR/EDR peer acting as an SDP server returns discovery-response records that are stored verbatim in the client receive buffer and parsed via the public bt_sdp_get_attr()/bt_sdp_has_attr()/bt_sdp_record_parse() helpers. The over-read is bounded to a single byte that is used only as an internal length selector and is never leaked to the attacker; subsequent length checks then reject the malformed record. Realistic impact is therefore limited to an edge-case denial of service (a fault only if the record ends exactly at a mapped-memory boundary, or a deterministic assert panic when CONFIG_ASSERT=y). Affects Zephyr v4.3.0 and v4.4.0; fixed by adding sizeof(type) to the length check.
Title Bluetooth Classic SDP parser truncation bug in bt_sdp_parse_attribute() leads to reachable assertion and possible out-of-bounds read Out-of-bounds read in Bluetooth Classic SDP attribute parsing (`bt_sdp_parse_attribute`)
Weaknesses CWE-617
References

Tue, 23 Jun 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 23 Jun 2026 02:45:00 +0000

Type Values Removed Values Added
First Time appeared Zephyrproject-rtos
Zephyrproject-rtos zephyr
Vendors & Products Zephyrproject-rtos
Zephyrproject-rtos zephyr

Tue, 23 Jun 2026 00:30:00 +0000

Type Values Removed Values Added
Description A malformed Bluetooth Classic SDP attribute can trigger a reachable assertion in Zephyr's SDP parser. In subsys/bluetooth/host/classic/sdp.c, bt_sdp_parse_attribute() accepts an input buffer once it contains the 1-byte attribute type and 2-byte attribute id, but then unconditionally pulls an additional byte for the value type without verifying that the byte is present. A truncated 3-byte attribute (for example 09 00 09) therefore reaches net_buf_simple_pull() with insufficient remaining length, triggering the __ASSERT_NO_MSG(buf->len >= len) check and a kernel panic in assert-enabled builds (denial of service). In builds where assertions are disabled, parsing may continue past the end of the available buffer, leading to an out-of-bounds read and undefined behavior.
Title Bluetooth Classic SDP parser truncation bug in bt_sdp_parse_attribute() leads to reachable assertion and possible out-of-bounds read
Weaknesses CWE-20
CWE-617
References
Metrics cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H'}

Subscriptions

Zephyrproject-rtos Zephyr
cve-icon MITRE

Status: PUBLISHED

Assigner: zephyr

Published:

Updated: 2026-07-14T18:38:37.013Z

Reserved: 2026-06-02T15:24:24.388Z

Link: CVE-2026-10651

cve-icon Vulnrichment

Updated: 2026-06-23T12:19:40.873Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-23T02:30:16Z

Weaknesses