{"api_version":"1","generated_at":"2026-09-18T00:39:20+00:00","cve":"CVE-2026-90136","urls":{"html":"https://cve.report/CVE-2026-90136","api":"https://cve.report/api/cve/CVE-2026-90136.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-90136","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-90136"},"summary":{"title":"platform/x86/amd/hsmp: Reject negative power cap writes in hwmon","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86/amd/hsmp: Reject negative power cap writes in hwmon\n\nhsmp_hwmon_write() takes the user-supplied hwmon value as a signed long\nand assigns \"val / MICROWATT_PER_MILLIWATT\" to msg.args[0], which is a\n__u32.  MICROWATT_PER_MILLIWATT is an unsigned long, so a negative write\nto power1_cap (e.g. \"echo -1 > power1_cap\") is first converted to a huge\nunsigned value by the division and then stored into the u32 argument.\n\nAs a result a nonsensical, multi-gigawatt socket power limit is sent to\nthe SMU via HSMP_SET_SOCKET_POWER_LIMIT instead of the write being\nrejected.\n\nReject negative values with -EINVAL before the conversion.\n\nTested with HSMP enabled:\n\n  CAP=$(dirname $(grep -l amd_hsmp_hwmon \\\n        /sys/class/hwmon/hwmon*/name | head -1))/power1_cap\n\n  # negative write\n  echo -1000000 > $CAP ; echo \"ret=$?\"\n  # valid positive write must still work\n  echo 400000000 > $CAP ; echo \"ret=$?\"\n\nBefore:\n  # echo -1000000 > $CAP ; echo \"ret=$?\"\n  ret=0                             <- accepted; bogus limit sent to SMU\n  # echo 400000000 > $CAP ; echo \"ret=$?\"\n  ret=0\n\nAfter:\n  # echo -1000000 > $CAP ; echo \"ret=$?\"\n  bash: echo: write error: Invalid argument\n  ret=1                             <- rejected with -EINVAL\n  # echo 400000000 > $CAP ; echo \"ret=$?\"\n  ret=0                             <- valid write still works","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-17 17:17:06","updated_at":"2026-09-17 17:17:06"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/1b0a3d915320f1600e5ff43f8bc21b73118480b8","name":"https://git.kernel.org/stable/c/1b0a3d915320f1600e5ff43f8bc21b73118480b8","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3921bb8635ff2836622df1cdf3194d4f3c1835a4","name":"https://git.kernel.org/stable/c/3921bb8635ff2836622df1cdf3194d4f3c1835a4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2c09cadec116eba3fdbcb5d8d8641f6777d4a11f","name":"https://git.kernel.org/stable/c/2c09cadec116eba3fdbcb5d8d8641f6777d4a11f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-90136","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90136","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 92c025db52bb94a032eb3d473bb81e62c19ddbd3 2c09cadec116eba3fdbcb5d8d8641f6777d4a11f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 92c025db52bb94a032eb3d473bb81e62c19ddbd3 1b0a3d915320f1600e5ff43f8bc21b73118480b8 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 92c025db52bb94a032eb3d473bb81e62c19ddbd3 3921bb8635ff2836622df1cdf3194d4f3c1835a4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.16","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.16 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.52 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/platform/x86/amd/hsmp/hwmon.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"2c09cadec116eba3fdbcb5d8d8641f6777d4a11f","status":"affected","version":"92c025db52bb94a032eb3d473bb81e62c19ddbd3","versionType":"git"},{"lessThan":"1b0a3d915320f1600e5ff43f8bc21b73118480b8","status":"affected","version":"92c025db52bb94a032eb3d473bb81e62c19ddbd3","versionType":"git"},{"lessThan":"3921bb8635ff2836622df1cdf3194d4f3c1835a4","status":"affected","version":"92c025db52bb94a032eb3d473bb81e62c19ddbd3","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/platform/x86/amd/hsmp/hwmon.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.16"},{"lessThan":"6.16","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.52","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.52","versionStartIncluding":"6.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"6.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.16","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86/amd/hsmp: Reject negative power cap writes in hwmon\n\nhsmp_hwmon_write() takes the user-supplied hwmon value as a signed long\nand assigns \"val / MICROWATT_PER_MILLIWATT\" to msg.args[0], which is a\n__u32.  MICROWATT_PER_MILLIWATT is an unsigned long, so a negative write\nto power1_cap (e.g. \"echo -1 > power1_cap\") is first converted to a huge\nunsigned value by the division and then stored into the u32 argument.\n\nAs a result a nonsensical, multi-gigawatt socket power limit is sent to\nthe SMU via HSMP_SET_SOCKET_POWER_LIMIT instead of the write being\nrejected.\n\nReject negative values with -EINVAL before the conversion.\n\nTested with HSMP enabled:\n\n  CAP=$(dirname $(grep -l amd_hsmp_hwmon \\\n        /sys/class/hwmon/hwmon*/name | head -1))/power1_cap\n\n  # negative write\n  echo -1000000 > $CAP ; echo \"ret=$?\"\n  # valid positive write must still work\n  echo 400000000 > $CAP ; echo \"ret=$?\"\n\nBefore:\n  # echo -1000000 > $CAP ; echo \"ret=$?\"\n  ret=0                             <- accepted; bogus limit sent to SMU\n  # echo 400000000 > $CAP ; echo \"ret=$?\"\n  ret=0\n\nAfter:\n  # echo -1000000 > $CAP ; echo \"ret=$?\"\n  bash: echo: write error: Invalid argument\n  ret=1                             <- rejected with -EINVAL\n  # echo 400000000 > $CAP ; echo \"ret=$?\"\n  ret=0                             <- valid write still works"}],"providerMetadata":{"dateUpdated":"2026-09-17T16:06:35.190Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/2c09cadec116eba3fdbcb5d8d8641f6777d4a11f"},{"url":"https://git.kernel.org/stable/c/1b0a3d915320f1600e5ff43f8bc21b73118480b8"},{"url":"https://git.kernel.org/stable/c/3921bb8635ff2836622df1cdf3194d4f3c1835a4"}],"title":"platform/x86/amd/hsmp: Reject negative power cap writes in hwmon","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-90136","datePublished":"2026-09-17T16:06:35.190Z","dateReserved":"2026-09-11T19:38:34.788Z","dateUpdated":"2026-09-17T16:06:35.190Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-17 17:17:06","lastModifiedDate":"2026-09-17 17:17:06","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"90136","Ordinal":"1","Title":"platform/x86/amd/hsmp: Reject negative power cap writes in hwmon","CVE":"CVE-2026-90136","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"90136","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nplatform/x86/amd/hsmp: Reject negative power cap writes in hwmon\n\nhsmp_hwmon_write() takes the user-supplied hwmon value as a signed long\nand assigns \"val / MICROWATT_PER_MILLIWATT\" to msg.args[0], which is a\n__u32.  MICROWATT_PER_MILLIWATT is an unsigned long, so a negative write\nto power1_cap (e.g. \"echo -1 > power1_cap\") is first converted to a huge\nunsigned value by the division and then stored into the u32 argument.\n\nAs a result a nonsensical, multi-gigawatt socket power limit is sent to\nthe SMU via HSMP_SET_SOCKET_POWER_LIMIT instead of the write being\nrejected.\n\nReject negative values with -EINVAL before the conversion.\n\nTested with HSMP enabled:\n\n  CAP=$(dirname $(grep -l amd_hsmp_hwmon \\\n        /sys/class/hwmon/hwmon*/name | head -1))/power1_cap\n\n  # negative write\n  echo -1000000 > $CAP ; echo \"ret=$?\"\n  # valid positive write must still work\n  echo 400000000 > $CAP ; echo \"ret=$?\"\n\nBefore:\n  # echo -1000000 > $CAP ; echo \"ret=$?\"\n  ret=0                             <- accepted; bogus limit sent to SMU\n  # echo 400000000 > $CAP ; echo \"ret=$?\"\n  ret=0\n\nAfter:\n  # echo -1000000 > $CAP ; echo \"ret=$?\"\n  bash: echo: write error: Invalid argument\n  ret=1                             <- rejected with -EINVAL\n  # echo 400000000 > $CAP ; echo \"ret=$?\"\n  ret=0                             <- valid write still works","Type":"Description","Title":"platform/x86/amd/hsmp: Reject negative power cap writes in hwmon"}]}}}