{"cve":"CVE-2026-64186","nvd":{"published":"2026-07-19T16:18:01.037","modified":"2026-08-11T20:03:12.163","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd: Remove latent out-of-bounds access in IOMMU debugfs\n\nIn iommu_mmio_write() and iommu_capability_write(), the variables\ndbg_mmio_offset and dbg_cap_offset are declared as int. However, they\nare populated using kstrtou32_from_user(). If a user provides a\nsufficiently large value, it can become a negative integer.\n\nPrior to this patch, the AMD IOMMU debugfs implementation was already\nprotected by different mechanisms.\n\n1. #define OFS_IN_SZ 8 ensures the user string <= 8 bytes, so\n   e.g. 0xffffffff isn't a valid input.\n\n  if (cnt > OFS_IN_SZ)\n     return -EINVAL;\n\n2. Implicit type promotion in iommu_mmio_write(), dbg_mmio_offset is int\n   and iommu->mmio_phys_end is u64\n\n  if (dbg_mmio_offset > iommu->mmio_phys_end - sizeof(u64))\n      return -EINVAL;\n\n3. The show handlers would currently catch the negative number and\n   refuse to perform the read.\n\nReplace kstrtou32_from_user() with kstrtos32_from_user() to parse the\ninput, and check for negative values to explicitly prevent out-of-bounds\nmemory accesses directly in iommu_mmio_write() and\niommu_capability_write().","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","score":7.1},"cwes":["CWE-125"],"references":["https://git.kernel.org/stable/c/488d2c76bd9f78433a70690d1054bfae3d39a407","https://git.kernel.org/stable/c/62f9dfbf1aceae88b03c5ca08f7d36e943939dec","https://git.kernel.org/stable/c/8dfd3d8d74435344ee8dc9237596959c8b2a6cbe"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:45:36.895656543+00:00"},"epss":{"cve":"CVE-2026-64186","score":0.00164,"percentile":0.0561,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}