CVE-2026-90136platform/x86/amd/hsmp: Reject negative power cap writes in hwmon
- —Not scoredno CVSS score yet
- 0.21%Exploitation in 30 daysEPSS · top 89% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: platform/x86/amd/hsmp: Reject negative power cap writes in hwmon hsmp_hwmon_write() takes the user-supplied hwmon value as a signed long and assigns "val / MICROWATT_PER_MILLIWATT" to msg.args[0], which is a __u32. MICROWATT_PER_MILLIWATT is an unsigned long, so a negative write to power1_cap (e.g. "echo -1 > power1_cap") is first converted to a huge unsigned value by the division and then stored into the u32 argument. As a result a nonsensical, multi-gigawatt socket power limit is sent to the SMU via HSMP_SET_SOCKET_POWER_LIMIT instead of the write being rejected. Reject negative values with -EINVAL before the conversion. Tested with HSMP enabled: CAP=$(dirname $(grep -l amd_hsmp_hwmon \ /sys/class/hwmon/hwmon*/name | head -1))/power1_cap # negative write echo -1000000 > $CAP ; echo "ret=$?" # valid positive write must still work echo 400000000 > $CAP ; echo "ret=$?" Before: # echo -1000000 > $CAP ; echo "ret=$?" ret=0 <- accepted; bogus limit sent to SMU # echo 400000000 > $CAP ; echo "ret=$?" ret=0 After: # echo -1000000 > $CAP ; echo "ret=$?" bash: echo: write error: Invalid argument ret=1 <- rejected with -EINVAL # echo 400000000 > $CAP ; echo "ret=$?" ret=0 <- valid write still works
Timeline
ID reserved
By Linux
- 6 days later
· 6 days later
Published
- 32 days later
· 32 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.21% · top 89% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected 92c025db52bb94a032eb3d473bb81e62c19ddbd3 – < 2c09cadec116eba3fdbcb5d8d8641f6777d4a11f
- affected 92c025db52bb94a032eb3d473bb81e62c19ddbd3 – < 1b0a3d915320f1600e5ff43f8bc21b73118480b8
- affected 92c025db52bb94a032eb3d473bb81e62c19ddbd3 – < 3921bb8635ff2836622df1cdf3194d4f3c1835a4
- affected 6.16
- unaffected < 6.16
- unaffected 6.18.52 – ≤ 6.18.*
- unaffected 7.2.6 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-81729 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-90136)Record last updated .