# CVE-2026-64501: iio: adc: ad_sigma_delta: fix CS held asserted and state leaks

> A race condition in the Linux kernel ADC driver allows concurrent SPI access and leaves devices in an invalid state, potentially causing denial of service.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Jul 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-64501, DEBIAN-CVE-2026-64501, GHSA-8j65-cc62-w2hg, ROOT-OS-UBUNTU-2204-CVE-2026-64501, UBUNTU-CVE-2026-64501

## What is CVE-2026-64501?

CVE-2026-64501 is a high-severity vulnerability in Linux, published on 25 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

iio: adc: ad_sigma_delta: fix CS held asserted and state leaks

In ad_sigma_delta_single_conversion(), set_mode(AD_SD_MODE_IDLE) and
disable_one() were called from the out: block while keep_cs_asserted
was still true. This caused any SPI transfer issued by those callbacks
to carry cs_change=1, leaving CS permanently asserted after the
conversion. Fix by moving both calls into the out_unlock: block, after
keep_cs_asserted is cleared, matching the pattern already used in
ad_sd_calibrate().

In the error path of ad_sd_buffer_postenable(), if an operation fails
after set_mode(AD_SD_MODE_CONTINUOUS) has already succeeded (e.g.
spi_offload_trigger_enable()), the device is left in continuous
conversion mode with CS physically asserted. Additionally,
bus_locked remaining true after spi_bus_unlock() causes subsequent
SPI operations to call spi_sync_locked() without the bus lock actually
held, allowing concurrent SPI access.

Fix the error path by clearing keep_cs_asserted first, then calling
set_mode(AD_SD_MODE_IDLE) to revert the device mode and deassert CS,
then clearing bus_locked before releasing the bus.

For devices that implement neither set_mode nor disable_one (such as
MAX11205, which has no physical CS pin), no SPI transfer is issued
during cleanup and the cs_change flag has no effect on any physical
line.

## Which versions are affected by CVE-2026-64501?


## How do I fix CVE-2026-64501?

Apply the vendor's patch.

## Is CVE-2026-64501 being exploited?

There is no known exploitation of CVE-2026-64501 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64501 and fix it if it is affected.

What it is: CVE-2026-64501 is a high-severity vulnerability in Linux, published on 25 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-2026-64501 in the wild and no public exploit code.

Affected product: Linux. 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-2026-64501/ (Markdown: https://insights.sbomify.com/CVE-2026-64501/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64501
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64501
- OSV: https://osv.dev/vulnerability/CVE-2026-64501

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64501/
Summaries are generated and may contain mistakes; the official description above is the record.