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CVE-2026-18748— Out-of-bounds read in Bluetooth Classic A2DP codec information element handling

Quick assessment

Affected
zephyrproject zephyr
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

经典蓝牙 A2DP 主机将编解码器信息元素（IE）存储在 结构中，该结构包含一个单字节的长度字段 和一个固定长度为 8 字节的 数组。当 AVDTP 对等端发送长度超过 8 字节的编解码器 IE 时， （位于 ）仅复制了前 8 个字节，却将攻击者指定的完整长度赋值给 ，随后将该不一致的结构通过 持久化到应用程序的 中。 和 也存在相同的“截断复制但保留原长度”的模式。 后续所有使用者均信任 字段。特别是针对传入的 AVDTP GET_CONFIGURATION 请求的响应处理函数 ，会执行 。因此，若一个已配对的

CVSS 3.5 · Low

Affected Version Matrix 1

VendorProduct Version RangeStatus
zephyrproject zephyr 4.3.0≤ 4.4.2 affected
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I. Basic Information for CVE-2026-18748

Vulnerability Information
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Vulnerability Title
Out-of-bounds read in Bluetooth Classic A2DP codec information element handling
Source: CVE Program / CVE List V5
Vulnerability 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. 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
zephyrproject zephyr 4.3.0 ~ 4.4.2 -

II. Public POCs for CVE-2026-18748

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III. Intelligence Information for CVE-2026-18748

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Patches & Fixes for CVE-2026-18748 (1)

Vendor Advisories for CVE-2026-18748 (1)

Same Patch Batch · zephyrproject · 2026-10-21 · 8 CVEs total

CVE-2026-19676 7.8 HIGH PECI transfer syscall verifier does not validate embedded user buffer pointers, allowing a
CVE-2026-79976 7.1 HIGH NULL pointer dereference in the MCTP I2C+GPIO target binding triggerable by a peer I2C con
CVE-2026-78118 7.0 HIGH Race condition on kernel wait queues: unlocked z_waitq_head() read in the timer expiration
CVE-2026-78119 6.3 MEDIUM Out-of-bounds write in the Nuvoton NPCX eSPI Target-Attached-Flash receive path from an un
CVE-2026-19947 5.3 MEDIUM Missing kernel object permission check in devmux syscalls allows unprivileged user threads
CVE-2026-78116 5.2 MEDIUM Double free of an RTIO submission in the Broadcom AFBR-S50 sensor driver data-evaluation e
CVE-2026-78117 4.2 MEDIUM Race condition on shared HCI TX descriptor in the Infineon PSOC 6 BLESS Bluetooth driver c

IV. Related Vulnerabilities

Same product: zephyr
Same vendor: zephyrproject
Same weakness: CWE-125

V. Comments for CVE-2026-18748

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