ZephyrProject Zephyr up to 4.4.2 A2DP Host a2dp.c a2dp_process_config_ind len out-of-bounds

Summaryinfo

A vulnerability has been found in ZephyrProject Zephyr up to 4.4.2 and classified as problematic. Affected is the function a2dp_process_config_ind of the file subsys/bluetooth/host/classic/a2dp.c of the component A2DP Host. The manipulation of the argument len leads to out-of-bounds. This vulnerability is listed as CVE-2026-18748. The attack may be initiated remotely. There is no available exploit. Applying a patch is the recommended action to fix this issue.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in ZephyrProject Zephyr up to 4.4.2. This issue affects the function a2dp_process_config_ind of the file subsys/bluetooth/host/classic/a2dp.c of the component A2DP Host. The manipulation of the argument len with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality. The summary by CVE is:

The Bluetooth Classic A2DP host stores a codec Information Element (IE) in struct bt_a2dp_codec_ie, a one-byte len field plus a fixed 8-byte codec_ie[] array. When an AVDTP peer sent a codec IE longer than 8 bytes, a2dp_process_config_ind() in subsys/bluetooth/host/classic/a2dp.c copied only the first 8 bytes but assigned the full, attacker-chosen length to len, and then persisted that inconsistent structure into the application's struct bt_a2dp_stream via stream->codec_config. bt_a2dp_get_config_cb() and bt_a2dp_set_config_cb() had the same truncate-the-copy-but-keep-the-length pattern. Every later consumer trusts len. In particular the responder for an incoming AVDTP GET_CONFIGURATION, a2dp_get_config_ind(), executes net_buf_add_mem(rsp_buf, &ep->stream->codec_config.codec_ie[0], ep->stream->codec_config.len), so a paired BR/EDR peer that first sends a SET_CONFIGURATION carrying an oversized codec IE and then requests the configuration back causes the stack to read up to roughly 245 bytes past the end of the 8-byte array and transmit them in the response. codec_config is the last member of struct bt_a2dp_stream, so the read runs into memory adjacent to the application's stream object. The same inconsistency is also handed to the config_req(), reconfig_req() and get_config_rsp() application callbacks, where a natural memcpy() of len bytes performs a further out-of-bounds read. Reaching the on-air disclosure requires CONFIG_BT_CLASSIC with CONFIG_BT_A2DP, an AVDTP peer that has completed pairing (the AVDTP L2CAP channel requires BT_SECURITY_L2), and a local endpoint registered for a non-SBC codec — BT_A2DP_MPEG1/BT_A2DP_MPEG2/BT_A2DP_ATRAC/BT_A2DP_VENDOR via BT_A2DP_EP_INIT() — because the SBC branch already pins the IE length to 4 bytes. The bt_a2dp_get_config_cb() response path has no such gate and hands the lying length to any application. There is no out-of-bounds write: the net_buf tailroom check bounds the destination, so the impact is limited to disclosure of a bounded region of adjacent RAM to the peer. The fix replaces the hardcoded BT_A2DP_MAX_IE_LENGTH with the configurable CONFIG_BT_A2DP_CODEC_MAX_IE_LEN (default 8, range 4–253), sizes codec_ie[] from it, and rejects any received IE that exceeds it instead of silently truncating, so len can no longer exceed the number of valid bytes.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-18748 since 08/03/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details are known, but no exploit is available.

Applying the patch c5f649f4714e625362fbaa93ffd7419f9c27342b is able to eliminate this problem.

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Productinfo

Type

• Project Management Software

Vendor

• ZephyrProject

Name

• Zephyr

Version

• 4.4.0
• 4.4.1
• 4.4.2

CPE 2.3info

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CPE 2.2info

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