CVE-2026-99274

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix fiemap wild read on empty truncated response smb3_fiemap() treats -E2BIG from SMB2_ioctl() as a truncated range blob and loops for the next chunk. If the server reports STATUS_BUFFER_OVERFLOW with OutputCount == 0, SMB2_ioctl() returns -E2BIG with out_data == NULL and out_data_len == 0, and the existing length checks accept the empty result. The loop then evaluates next = out_data[num - 1].file_offset + ... with num == 0, reading 16 bytes before NULL. Reject a truncated range blob that contains no range, so the resume offset is never computed from an empty response. Also require the last range in a truncated blob to advance the resume offset without overflowing, and to stay within the requested range; a malicious or broken server could otherwise make no progress or underflow len and loop forever. Free the previous response buffer before retrying. Reproduced on 6.6.87.2 with a malicious SMB2 server that answers FSCTL_QUERY_ALLOCATED_RANGES with STATUS_BUFFER_OVERFLOW and OutputCount == 0; an FS_IOC_FIEMAP ioctl on the mount oopses in cifs_fiemap() with CR2 = fffffffffffffff8. The code path is unchanged on mainline.

Severity

Not scored

CVSS score

Not available

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-11-07 14:17:02.730000

Last modified

2026-11-07 14:17:02.730000

View original CVE JSON

{
  "id": "CVE-2026-99274",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-11-07T14:17:02.730",
  "lastModified": "2026-11-07T14:17:02.730",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix fiemap wild read on empty truncated response\n\nsmb3_fiemap() treats -E2BIG from SMB2_ioctl() as a truncated range blob\nand loops for the next chunk. If the server reports\nSTATUS_BUFFER_OVERFLOW with OutputCount == 0, SMB2_ioctl() returns\n-E2BIG with out_data == NULL and out_data_len == 0, and the existing\nlength checks accept the empty result. The loop then evaluates\n\n\tnext = out_data[num - 1].file_offset + ...\n\nwith num == 0, reading 16 bytes before NULL.\n\nReject a truncated range blob that contains no range, so the resume\noffset is never computed from an empty response. Also require the last\nrange in a truncated blob to advance the resume offset without\noverflowing, and to stay within the requested range; a malicious or\nbroken server could otherwise make no progress or underflow len and loop\nforever. Free the previous response buffer before retrying.\n\nReproduced on 6.6.87.2 with a malicious SMB2 server that answers\nFSCTL_QUERY_ALLOCATED_RANGES with STATUS_BUFFER_OVERFLOW and\nOutputCount == 0; an FS_IOC_FIEMAP ioctl on the mount oopses in\ncifs_fiemap() with CR2 = fffffffffffffff8. The code path is unchanged\non mainline."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "fs/smb/client/smb2ops.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "2f3ebaba13cebd8badfb9aed31c0cf3cc82eb4f4",
              "lessThan": "4a426ca5be7e3dedbe76575b967db04fbf01136f",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "2f3ebaba13cebd8badfb9aed31c0cf3cc82eb4f4",
              "lessThan": "31f6dbb29fe17fa9595c7e8b19fd92915b03a4ca",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "2f3ebaba13cebd8badfb9aed31c0cf3cc82eb4f4",
              "lessThan": "f5baa17a0f316c235d61623ac8e8fb32c2b3c0cc",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "fs/smb/client/smb2ops.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "5.2",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "5.2",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.61",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.3.2",
              "lessThanOrEqual": "7.3.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.4-rc1",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {},
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/31f6dbb29fe17fa9595c7e8b19fd92915b03a4ca",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/4a426ca5be7e3dedbe76575b967db04fbf01136f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f5baa17a0f316c235d61623ac8e8fb32c2b3c0cc",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}