{"id":"CVE-2026-18748","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-18748","generatedAt":"2026-10-28T00:57:18.793Z","title":"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…","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.","published":"2026-10-21T19:17:03.000Z","lastModified":"2026-10-23T22:17:00.000Z","status":"Awaiting Analysis","sourceIdentifier":"vulnerabilities@zephyrproject.org","cvss":{"version":"3.1","score":3.5,"severity":"LOW","vector":"CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"},"cwe":["CWE-125"],"affected":[],"epss":{"score":0.00203,"percentile":0.10123,"date":"2026-10-26","history":[{"date":"2026-10-22","score":0.00158,"percentile":0.04563}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.20%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-21T19:17:03.000Z","detail":{"score":"3.5","severity":"LOW","publishedAt":"2026-10-21T19:17:02.503Z"},"summary":"New CVE, low severity (CVSS 3.5)."}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/c5f649f4714e625362fbaa93ffd7419f9c27342b","source":"vulnerabilities@zephyrproject.org"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-6qq5-25mp-x5rg","source":"vulnerabilities@zephyrproject.org"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-18748","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}