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.
- 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
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.
Sources
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.