CVE-2026-99022: regulator: ltc3676: don't read the write-only HRST and CLIRQ registers
In the Linux kernel, the following vulnerability has been resolved:
regulator: ltc3676: don't read the write-only HRST and CLIRQ registers
HRST (0x1e) and CLIRQ (0x1f) are write-only command strobes. Writing HRST triggers a hard reset of the chip and writing CLIRQ clears the interrupt; reading them returns nothing useful, and the read itself fires the command.
The result is that a plain register dump resets the board:
cat /sys/kernel/debug/regmap/2-003c/registers
walks every readable register, hits HRST, and the board reboots.
Split the callback back in two so HRST and CLIRQ stay writable but are no longer readable. The readable range is left unchanged (LTC3676BUCK1 ... LTC3676IRQSTAT).
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.18.57 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 7.2.11 - Configuration
Keep HRST and CLIRQ writable but exclude them from readable registers and register dumps; reads must not be performed because reading either write-only command strobe triggers its command.
Linux kernel regulator ltc3676 HRST (0x1e) and CLIRQ (0x1f) register readability = disabled
Event History
Frequently Asked Questions
Who is exposed to this issue?
Systems using the Linux kernel LTC3676 regulator driver are exposed when the LTC3676 device is present and its regmap debug register dump is accessed. The described trigger is reading /sys/kernel/debug/regmap/2-003c/registers.
What action triggers the reboot?
A register dump that reads the HRST register can trigger the chip's hard-reset command because HRST is a write-only command strobe. The example command is cat /sys/kernel/debug/regmap/2-003c/registers, which walks readable registers and causes the board to reboot when it reaches HRST.
Are normal regulator register reads affected?
The fix leaves the readable range from LTC3676_BUCK1 through LTC3676_IRQSTAT unchanged. HRST and CLIRQ remain writable, but are no longer exposed as readable registers.
What can be done before the fix is deployed?
Do not perform regmap register dumps for the affected LTC3676 device, particularly through the debugfs registers file. Avoid tooling or diagnostic procedures that read every register, since reading HRST or CLIRQ can issue their command actions.