# CVE-2026-75085: Out-of-bounds read from received-frame length underflow in the STM32WBA IEEE 802.15.4 driver


- **Severity:** Medium 4.2 (`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 14 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** GHSA-w7pm-4r95-c9vr

## What is CVE-2026-75085?

CVE-2026-75085 is a medium-severity vulnerability in zephyrproject zephyr, published on 14 Oct 2026. 

### Official description

The STM32WBA IEEE 802.15.4 driver in drivers/ieee802154/ieee802154_stm32wba.c computed the packet length of a received frame as pkt_len = rx_frame->length - IEEE802154_FCS_LENGTH without first checking that the radio-reported length could hold an FCS. pkt_len is a uint8_t, so a reported length of 0 or 1 wrapped to 254 or 255. The only bound on the resulting value was __ASSERT_NO_MSG(pkt_len <= CONFIG_NET_BUF_DATA_SIZE), which compiles to nothing in the default production configuration (CONFIG_ASSERT=n).

The length originates in the ST link-layer receive-done metadata (p_metadata->length, stored by stm32wba_802154_receive_done()), and ultimately in the PHY header of a frame received over the air, so it is influenced by any attacker within radio range of the device. Reaching the underflow requires the vendor link layer to surface a frame shorter than the FCS with no error; the driver performed no validation of its own on that value.

When the underflow occurs, stm32wba_802154_rx_thread() calls net_pkt_write(pkt, rx_frame->psdu, pkt_len) with a length of about 254 bytes against a receive buffer that holds at most one PHY packet (IEEE802154_MAX_PHY_PACKET_SIZE, 127 bytes). This reads roughly 128 bytes past the end of the radio receive buffer and copies that adjacent memory into a network packet that is submitted to the networking stack, giving an out-of-bounds read with a potential disclosure of adjacent RAM plus needless oversized packet allocation in the RX thread.

The fix rejects a frame whose reported length is smaller than IEEE802154_FCS_LENGTH before the subtraction, and replaces the compiled-out assertion with a runtime length check that drops oversized frames — matching the runtime check already present in drivers/ieee802154/ieee802154_nrf5.c.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-75085?


## How do I fix CVE-2026-75085?

No fix has been published for CVE-2026-75085 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-75085 being exploited?

There is no known exploitation of CVE-2026-75085 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-75085 and fix it if it is affected.

What it is: CVE-2026-75085 is a medium-severity vulnerability in zephyrproject zephyr, published on 14 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-75085 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-2026-75085/ (Markdown: https://insights.sbomify.com/CVE-2026-75085/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-75085
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-75085
- OSV: https://osv.dev/vulnerability/CVE-2026-75085

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-75085/
Summaries are generated and may contain mistakes; the official description above is the record.