{"id":"CVE-2026-64186","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-64186","summary":"iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs","details":"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().","published":"2026-07-19T15:41:08.054Z","modified":"2026-08-01T03:33:00.492241350Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.18.34"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/488d2c76bd9f78433a70690d1054bfae3d39a407"},{"type":"WEB","url":"https://git.kernel.org/stable/c/62f9dfbf1aceae88b03c5ca08f7d36e943939dec"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8dfd3d8d74435344ee8dc9237596959c8b2a6cbe"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64186.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64186"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-01T03:33:00.492241350Z"}}