{"id":"CVE-2026-18748","revision":"a7a5a643504a4efa9450c4d1411198e4","records":[{"revision":"a7a5a643504a4efa9450c4d1411198e4","observedAt":"2026-10-23T22:48:20.692+00:00","statement":{"source":"cve-program","id":"CVE-2026-18748","aliases":[],"title":"Out-of-bounds read in Bluetooth Classic A2DP codec information element handling","description":"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.\n\nEvery 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.\n\nReaching 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.\n\nThe 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.","state":0,"publishedAt":"2026-10-21T18:19:29.937+00:00","modifiedAt":"2026-10-23T21:31:20.955+00:00","affected":[{"ecosystem":"https://github.com/zephyrproject-rtos/zephyr","name":"zephyr","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"zephyrproject\",\n                    \"product\": \"zephyr\",\n                    \"collectionURL\": \"https://github.com/zephyrproject-rtos/zephyr\",\n                    \"packageName\": \"zephyr\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"programFiles\": [\n                        \"include/zephyr/bluetooth/classic/a2dp.h\",\n                        \"subsys/bluetooth/host/classic/Kconfig\",\n                        \"subsys/bluetooth/host/classic/a2dp.c\"\n                    ],\n                    \"programRoutines\": [\n                        {\n                            \"name\": \"a2dp_get_config_ind\"\n                        },\n                        {\n                            \"name\": \"a2dp_process_config_ind\"\n                        },\n                        {\n                            \"name\": \"bt_a2dp_get_config_cb\"\n                        }\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"4.3.0\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\",\n                            \"lessThanOrEqual\": \"4.4.2\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","score":3.5,"severity":"LOW"}],"references":["https://github.com/zephyrproject-rtos/zephyr/commit/c5f649f4714e625362fbaa93ffd7419f9c27342b","https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6qq5-25mp-x5rg"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-18748","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-18748","identifiers":["CVE-2026-18748"]},"retained":false,"historicalAffected":[]}],"coverage":[]}