{
  "threat_severity" : "Moderate",
  "public_date" : "2026-05-01T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path",
    "id" : "2464396",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2464396"
  },
  "cvss3" : {
    "cvss3_base_score" : "7.0",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
    "status" : "draft"
  },
  "cwe" : "CWE-805",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nsmb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path\nsmb2_ioctl_query_info() has two response-copy branches: PASSTHRU_FSCTL\nand the default QUERY_INFO path.  The QUERY_INFO branch clamps\nqi.input_buffer_length to the server-reported OutputBufferLength and then\ncopies qi.input_buffer_length bytes from qi_rsp->Buffer to userspace, but\nit never verifies that the flexible-array payload actually fits within\nrsp_iov[1].iov_len.\nA malicious server can return OutputBufferLength larger than the actual\nQUERY_INFO response, causing copy_to_user() to walk past the response\nbuffer and expose adjacent kernel heap to userspace.\nGuard the QUERY_INFO copy with a bounds check on the actual Buffer\npayload.  Use struct_size(qi_rsp, Buffer, qi.input_buffer_length)\nrather than an open-coded addition so the guard cannot overflow on\n32-bit builds.", "A flaw was found in the Linux kernel's Server Message Block (SMB) client. A malicious server can exploit an out-of-bounds read vulnerability by manipulating the OutputBufferLength during a QUERY_INFO operation. This can lead to the exposure of sensitive kernel memory to userspace, resulting in information disclosure." ],
  "statement" : "SMB2 `QUERY_INFO` handling could read out of bounds on untrusted server responses. Red Hat treats this as SMB client parser hardening against malicious servers. Install corrected kernels; `cifs` unload reduces client exposure where acceptable.",
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "fix_state" : "Affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10"
  }, {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2026-31708\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-31708\nhttps://lore.kernel.org/linux-cve-announce/2026050121-CVE-2026-31708-f27c@gregkh/T" ],
  "name" : "CVE-2026-31708",
  "mitigation" : {
    "value" : "To mitigate this issue, prevent the cifs module from being loaded. See https://access.redhat.com/solutions/41278 for instructions.",
    "lang" : "en:us"
  },
  "csaw" : false
}