Power-limit corruption via unchecked negative hwmon writes
Published Sep 17, 2026 · Updated Sep 17, 2026
Input validation failure in Linux 6.16 AMD HSMP allows local users to send invalid socket power limits via negative power1_cap writes. The hsmp_hwmon_write() function divides a signed input by an unsigned conversion factor and stores the result in a 32-bit unsigned argument, turning negative values into enormous limits sent to the SMU. Exploitation requires supported AMD hardware, enabled HSMP, and write access to the hwmon attribute; the demonstrated consequence is an invalid power-limit command, not a confirmed crash or reboot.
Summary
What happened
Input validation failure in Linux 6.16 AMD HSMP allows local users to send invalid socket power limits via negative power1_cap writes. The hsmp_hwmon_write() function divides a signed input by an unsigned conversion factor and stores the result in a 32-bit unsigned argument, turning negative values into enormous limits sent to the SMU. Exploitation requires supported AMD hardware, enabled HSMP, and write access to the hwmon attribute; the demonstrated consequence is an invalid power-limit command, not a confirmed crash or reboot.
The record
- CVE
- CVE-2026-90136
- Published
- Sep 17, 2026
- Updated
- Sep 17, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-190
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 17, 2026CVE publishedPublication date reported by the CVE source.
- Sep 17, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=6.16
- Affected versionversion=92c025db52bb94a032eb3d473bb81e62c19ddbd3 <1b0a3d915320f1600e5ff43f8bc21b73118480b8
- Affected versionversion=92c025db52bb94a032eb3d473bb81e62c19ddbd3 <2c09cadec116eba3fdbcb5d8d8641f6777d4a11f
- Affected versionversion=92c025db52bb94a032eb3d473bb81e62c19ddbd3 <3921bb8635ff2836622df1cdf3194d4f3c1835a4
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
- HSMP negative power-cap write reproducerproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Get started to see how Hinoki identifies affected software and validates exploitability in your environment.
Get started