CVE-2026-99275

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: reject short SESSION_SETUP responses smb2_check_message() accepts frames shorter than struct smb2_pdu when the SMB2 status is non-zero, before the minimum-PDU check added by b4694f269e66d. A 64-byte STATUS_MORE_PROCESSING_REQUIRED SESSION_SETUP response is therefore accepted even though it cannot contain the SecurityBufferOffset and SecurityBufferLength fields. The parser then reads those fields from stale bytes left in the reused receive buffer by an earlier frame. With a long stale SecurityBufferLength, decode_ntlmssp_challenge() copies up to about 64 KB from beyond the receive object and sends the data back to the server in the NTLMv2 AUTHENTICATE target info. Reject short MPR SESSION_SETUP responses before the short-error path, and validate SecurityBufferOffset + SecurityBufferLength against the received response length before decoding the challenge. The ordering bypass is not new: the short-error early return predates b4694f269e66d, and the unvalidated SecurityBufferLength read predates the 2016 raw NTLMSSP split in 166cea4dc3a4, so all supported stable trees are affected. Reproduced on 6.6.87.2; the 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 14:17:02.850000

Last modified

2026-11-07 14:17:02.850000

View original CVE JSON

{
  "id": "CVE-2026-99275",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-11-07T14:17:02.850",
  "lastModified": "2026-11-07T14:17:02.850",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: reject short SESSION_SETUP responses\n\nsmb2_check_message() accepts frames shorter than struct smb2_pdu when\nthe SMB2 status is non-zero, before the minimum-PDU check added by\nb4694f269e66d. A 64-byte STATUS_MORE_PROCESSING_REQUIRED SESSION_SETUP\nresponse is therefore accepted even though it cannot contain the\nSecurityBufferOffset and SecurityBufferLength fields.\n\nThe parser then reads those fields from stale bytes left in the reused\nreceive buffer by an earlier frame. With a long stale\nSecurityBufferLength, decode_ntlmssp_challenge() copies up to about\n64 KB from beyond the receive object and sends the data back to the\nserver in the NTLMv2 AUTHENTICATE target info.\n\nReject short MPR SESSION_SETUP responses before the short-error path,\nand validate SecurityBufferOffset + SecurityBufferLength against the\nreceived response length before decoding the challenge.\n\nThe ordering bypass is not new: the short-error early return predates\nb4694f269e66d, and the unvalidated SecurityBufferLength read predates\nthe 2016 raw NTLMSSP split in 166cea4dc3a4, so all supported stable\ntrees are affected. Reproduced on 6.6.87.2; the path is unchanged on\nmainline."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "fs/smb/client/smb2misc.c",
            "fs/smb/client/smb2pdu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "5478f9ba9a34d660eb3227dcd16314689c51f946",
              "lessThan": "df63e01933886153e40706483b9635b2456ad91f",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "5478f9ba9a34d660eb3227dcd16314689c51f946",
              "lessThan": "4d8930afa3446041358a7db33e7b23a0bb9459b5",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "fs/smb/client/smb2misc.c",
            "fs/smb/client/smb2pdu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "3.6",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "3.6",
              "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/4d8930afa3446041358a7db33e7b23a0bb9459b5",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/df63e01933886153e40706483b9635b2456ad91f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}