{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-64074",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-64074"
  ],
  "published": "2026-07-19T15:41:06Z",
  "summary": "fs/statmount: fix slab out-of-bounds write in statmount_mnt_idmap",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/statmount: fix slab out-of-bounds write in statmount_mnt_idmap\n\nstatmount_mnt_idmap() writes one mapping with seq_printf() and then\nmanually advances seq->count to include the NUL separator.\n\nIf seq_printf() overflows, seq_set_overflow() sets seq->count to\nseq->size. The manual seq->count++ changes this to seq->size + 1.\nseq_has_overflowed() then no longer detects the overflow. The corrupted\ncount returns to statmount_string(), which later executes:\n\n    seq->buf[seq->count++] = '\\0';\n\nThis causes a 1-byte NULL out-of-bounds write on the dynamically\nallocated seq buffer.\n\nFix this by checking for overflow immediately after seq_printf().",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:13",
        "name": "linux"
      },
      "versions": [
        "1:6.18.29-1+rpt1",
        "1:6.18.33-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-2712",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v6",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v7",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v8",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.29+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.29-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-2712",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v6",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v7",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v8",
            "binary_version": "1:6.18.33-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.33+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.33-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.18.29-1+rpt1": {
            "linux_commit": "66318c5b5cd8145a662303af12ed39ac07eb27cc",
            "upstream_version": "6.18.29",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.34"
          },
          "1:6.18.33-1+rpt1": {
            "linux_commit": "95b85bebbedcaedfa7ca79116ed38b7376fba412",
            "upstream_version": "6.18.33",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.34"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-64074"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e37ea2c6f17f273813ea4e8e94c102591d598ce1"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/93614949dc86f068e3c32c32cf1ee2a2323177a7"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/a3bf0f28d4ba16e1f35f8c983bb04426b87e2a78"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The bug is reachable only through the statmount(2) syscall when requesting mount UID/GID map strings; there is no network, adjacent, or physical entry path to this code.\nAC:L - An attacker fully controls statmount mask, buffer sizing, mount paths/options, and idmap extent values to reliably drive seq_printf() to overflow at the vulnerable count++ site without depending on uncontrollable timing or layout.\nPR:L - Exploitation requires creating or querying an idmapped mount via statmount, which an unprivileged local user can do in their own user/mount namespaces where CAP_SYS_ADMIN is granted by user namespaces.\nUI:N - Triggering the flaw requires only the attacker's own statmount syscall and crafted namespace/mount setup; no action by another user or victim is needed.\nS:U - Impact is kernel heap corruption and potential privilege escalation within the same kernel security domain, not a cross-boundary escape such as VM guest-to-host.\nC:H - The flaw is a slab out-of-bounds write that corrupts adjacent heap memory; per kernel CVSS guidance, exploitable memory corruption warrants High confidentiality impact even if direct read is not guaranteed.\nI:H - A one-byte out-of-bounds NULL write into adjacent kmalloc slab objects can corrupt kernel metadata and be leveraged for arbitrary memory modification or code execution.\nA:H - Heap corruption from the out-of-bounds write can cause kernel oops/panic or destabilize the system, and memory-corruption bugs are scored as High availability impact."
    }
  }
}