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

> A shared buffer in Zephyr's Bluetooth Broadcast Assistant allows out-of-bounds writes via concurrent connections, enabling memory corruption or denial of service.

- **Severity:** Medium 6.4 (`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 11 Jul 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-73c7-3rh7-v5p9

## What is CVE-2026-10660?

CVE-2026-10660 is a medium-severity memory corruption vulnerability in zephyrproject zephyr, published on 11 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-10660?


## How do I fix CVE-2026-10660?

No fix has been published for CVE-2026-10660 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-10660 being exploited?

There is no known exploitation of CVE-2026-10660 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-10660 and fix it if it is affected.

What it is: CVE-2026-10660 is a medium-severity memory corruption vulnerability in zephyrproject zephyr, published on 11 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-10660 in the wild and no public exploit code.

Affected product: zephyrproject zephyr. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-10660/ (Markdown: https://insights.sbomify.com/CVE-2026-10660/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-10660
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-10660
- OSV: https://osv.dev/vulnerability/CVE-2026-10660

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-10660/
Summaries are generated and may contain mistakes; the official description above is the record.