# CVE-2026-79978: Out-of-bounds write in the ADXL345 sensor driver RTIO streaming FIFO read path - **Severity:** Low 3.6 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L`) - **Exploited in the wild:** Not known - **Fix available:** No - **Published:** 23 Oct 2026 - **Updated:** 23 Oct 2026 - **Also known as:** GHSA-4v56-r4qm-v964, UBUNTU-CVE-2026-79978 ## What is CVE-2026-79978? CVE-2026-79978 is a low-severity vulnerability in zephyrproject zephyr, published on 23 Oct 2026. ### Official description The RTIO streaming completion callback adxl345_process_fifo_samples_cb() in drivers/sensor/adi/adxl345/adxl345_stream.c clamps the amount of FIFO data it will report (read_len = MIN(fifo_bytes, buf_avail)) to the space actually returned by rtio_sqe_rx_buf(), but then queues one 6-byte bus read per hardware FIFO entry at consecutive offsets from read_buf, bounded by the device-reported entry count rather than by the clamp. When the allocated buffer is smaller than a full batch, the driver writes up to 186 bytes past the end of the allocation; a companion defect left data->fifo_total_bytes un-reset at batch start, so an aborted or errored chain could leave a stale write offset that pushes the next batch's writes out of bounds as well. A short buffer is an expected, first-class outcome of the RTIO allocator: rtio_block_pool_alloc() walks the requested size down one block at a time until a contiguous run is available, and the driver only demands sizeof(struct adxl345_fifo_data) + 6 bytes as its minimum. Any streaming configuration whose mempool block granularity is smaller than a full FIFO batch (204 bytes) — for example the sensor shell's RTIO_DEFINE_WITH_MEMPOOL(sensor_read_rtio, 8, 8, 32, 64, 4) used by sensor stream on fifo_wm incl, or the 16-byte-block streaming example in the documentation — takes this path whenever the pool is fragmented or the consuming thread falls behind. The out-of-bounds writes are performed by the I2C/SPI RTIO backend (DMA on many SoCs) into the shared RTIO block pool, corrupting neighbouring live buffers or, for a pool smaller than one batch, memory beyond the pool itself. The written bytes are accelerometer samples and the destination follows the allocation, so there is no controllable corruption primitive: the realistic impact is silent corruption of other RTIO consumers' data or a crash. Reaching it requires a board with an interrupt-wired ADXL345 built with CONFIG_ADXL345_STREAM, plus buffer-pool starvation, which a co-resident local workload can induce but which also occurs spontaneously under load; there is no network, USB or radio path to this code. Weakness: CWE-787 (Out-of-bounds Write) ## Which versions are affected by CVE-2026-79978? ## How do I fix CVE-2026-79978? No fix has been published for CVE-2026-79978 yet. Limit exposure of the affected software until one is available. ## Is CVE-2026-79978 being exploited? There is no known exploitation of CVE-2026-79978 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-79978 and fix it if it is affected. What it is: CVE-2026-79978 is a low-severity vulnerability in zephyrproject zephyr, published on 23 Oct 2026. Exploitation: There is no known exploitation of CVE-2026-79978 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-2026-79978/ (Markdown: https://insights.sbomify.com/CVE-2026-79978/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-79978 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-79978 - OSV: https://osv.dev/vulnerability/CVE-2026-79978 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-79978/ Summaries are generated and may contain mistakes; the official description above is the record.