CVE-2026-64502 iio: adc: ad_sigma_delta: fix clear_pending_event for registerless devices
A heap buffer overflow in the Linux kernel IIO ADC driver allows attackers to corrupt memory, potentially leading to code execution or system crashes.
- 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-2026-64502?
CVE-2026-64502 is a high-severity memory corruption 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 clear_pending_event for registerless devices
ad_sigma_delta_clear_pending_event() falls through to the status register read path for devices with has_registers = false and no rdy_gpiod. For such devices, ad_sd_read_reg() skips the address byte entirely and clocks raw MISO bytes with no address phase — making it byte-for-byte identical to reading conversion data. If a pending conversion result is present, this partially consumes it and corrupts the data stream for the subsequent ad_sd_read_reg() call in ad_sigma_delta_single_conversion().
Furthermore, with num_resetclks = 0 on these devices, data_read_len evaluates to 0. If the clocked byte has bit 7 clear, pending_event is set and the code attempts memset(data + 2, 0xff, 0 - 1), overflowing to SIZE_MAX and corrupting the heap.
Fix by returning 0 immediately when neither rdy_gpiod nor has_registers is set. This is safe for all current registerless devices: ad7191 and ad7780 (with powerdown GPIO) are reset between conversions by CS deassertion, so there is no stale result to drain; ad7780 (without powerdown GPIO) and max11205 are continuously-converting and cycle ~DRDY at the output data rate regardless of whether the previous result was read, so the next falling edge fires naturally.
A future registerless device that holds ~DRDY asserted until data is read would be broken by this early return and would require either num_resetclks set or a rdy-gpio.
The same heap corruption is reachable on any device with rdy_gpiod set but num_resetclks = 0: if the GPIO indicates a pending event, the drain path executes memset(data + 2, 0xff, 0 - 1) regardless of has_registers. Add an explicit data_read_len == 0 guard after the pending event check; the stale result is then consumed by the first ad_sd_read_reg() call in ad_sigma_delta_single_conversion().
Which versions are affected by CVE-2026-64502?
How do I fix CVE-2026-64502?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-64502 being exploited?
There is no known exploitation of CVE-2026-64502 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-64502, DEBIAN-CVE-2026-64502, GHSA-2vpq-89rm-wm52, ROOT-OS-UBUNTU-2204-CVE-2026-64502, UBUNTU-CVE-2026-64502.