{"schema":"threatline.record/2","record":{"id":"CVE-2026-18748","aliases":["GHSA-6qq5-25mp-x5rg"],"summary":"Out-of-bounds read in Bluetooth Classic A2DP codec information element handling","details":"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.","categories":["Unclassified"],"product":"zephyr","vendor":"zephyrproject","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-18748","source_modified_at":"2026-10-23T21:31:20.955Z","fetched_at":"2026-10-23T21:47:51.402276Z","product":"zephyr","vendor":"zephyrproject","versions":[{"version":"4.3.0","status":"affected","versionType":"semver","lessThanOrEqual":"4.4.2"}],"defaultStatus":"unaffected"}],"fixed_versions":[],"cvss":3.5,"severity":"Low","kev":{"listed":false},"epss":{"probability":0.00158,"percentile":0.04568,"score_date":"2026-10-23"},"published_at":"2026-10-21T18:19:29.937Z","modified_at":"2026-10-23T21:31:20.955Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-18748","fetched_at":"2026-10-23T21:47:51.402276Z","source_modified_at":"2026-10-23T21:31:20.955Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-18748","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/zephyrproject-rtos/zephyr/commit/c5f649f4714e625362fbaa93ffd7419f9c27342b","tags":["patch"]},{"source":"CVE List","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6qq5-25mp-x5rg"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"partial","assessed_at":"2026-10-23T20:42:53.954844Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-10-23T21:31:20.955Z","content_hash":"ad90ce46c09b5cc7a02392e80eccf72bab574241f4cabbf481965aaf2e2aa322"}}