CVE-2026-74549 is a vulnerability in Linux Kernel
Published on August 15, 2026
hwmon: (nct6775-core) Prevent access to unsupported weight registers
In the Linux kernel, the following vulnerability has been resolved:
hwmon: (nct6775-core) Prevent access to unsupported weight registers
Sashiko reports:
During initialization of the nct6116 chip, the driver sets data->pwm_num
to 5. However, it assigns several NCT6106 register arrays (such as
NCT6106_REG_WEIGHT_DUTY_STEP, NCT6106_REG_WEIGHT_TEMP_SEL, and
NCT6106_REG_WEIGHT_TEMP_*) to data->REG_PWM and data->REG_WEIGHT_TEMP.
These arrays only contain 3 elements.
In nct6775_update_pwm(), the driver iterates up to data->pwm_num. If
data->has_pwm has bits 3 or 4 set (which is structurally possible for
nct6116), the loop attempts to read elements at index 3 and 4 from these
3-element arrays. This results in a global out-of-bounds read, which can
be caught by KASAN.
Furthermore, the driver uses these garbage out-of-bounds values as
hardware register addresses for subsequent read and write operations. This
leads to invalid hardware register access, potentially causing hardware
misconfiguration or system crashes.
The underlying problem is that the chip does support up to five fan
control channels, but only the first three support weight control.
Fix the problem by extending the affected weight register arrays with
zeroed fields. The driver uses zeroed register addresses to determine
if a register is supported or not, and skips accesses for unsupported
registers.
Products Associated with CVE-2026-74549
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Affected Versions
Linux:- Version 29c7cb485b321c024dedc168bcbb04451176b163 and below 25b528816f5d83be5236dc182692369e8c9402b0 is affected.
- Version 29c7cb485b321c024dedc168bcbb04451176b163 and below 689082a4cb166a7ae9729f7b12339e69fdad6c52 is affected.
- Version 29c7cb485b321c024dedc168bcbb04451176b163 and below 1b722740ac5c2b2070f9ba922f4e0f227faf0246 is affected.
- Version 29c7cb485b321c024dedc168bcbb04451176b163 and below 4ad2972ef0e1bd1018ad7a72661a4636ed7daecc is affected.
- Version 29c7cb485b321c024dedc168bcbb04451176b163 and below d0b704e569ac3b8416d8e02270cdc9bf830ed395 is affected.
- Version 5.4 is affected.
- Before 5.4 is unaffected.
- Version 6.6.151, <= 6.6.* is unaffected.
- Version 6.12.103, <= 6.12.* is unaffected.
- Version 6.18.44, <= 6.18.* is unaffected.
- Version 7.1.8, <= 7.1.* is unaffected.
- Version 7.2-rc6, <= * is unaffected.