FKIE_CVE-2026-74494

Vulnerability from fkie_nvd - Published: 2026-08-15 13:17 - Updated: 2026-08-23 13:16
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: reject repeated SMB2 NEGOTIATE requests Unauthenticated client can send multiple successful SMB2 NEGOTIATE requests on one connection before SESSION_SETUP. While the connection is in KSMBD_SESS_NEED_SETUP, smb2_handle_negotiate() accepts another SMB3.1.1 NEGOTIATE and overwrites conn->preauth_info with a new allocation. Only the final allocation is freed when the connection is released, leaking one object for every additional successful request. A repeated SMB2 NEGOTIATE after a dialect has been selected is a protocol violation. MS-SMB2 section 3.3.5.4 requires the server to disconnect without replying in this case. Set the connection exiting when rejecting the request, in addition to suppressing the response. Reject SMB2 NEGOTIATE unless the connection is new or is waiting for the SMB2 NEGOTIATE that follows an SMB1 multi-protocol negotiate. Serialize both SMB1 and SMB2 negotiation paths under conn->srv_mutex, since they update connection-wide dialect and negotiation state. Move the locking contract to ksmbd_smb_negotiate_common(), where the state and dialect are selected, and add ksmbd_conn_new() for consistent state access.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0b1390cf2b6b91723b37c0909dd123f7a5eba1a7
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7e02cb30e8a1f5fc78cb10b220b06020e36d0bbe
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7fb8dbeb3f2868ae836ca12311d89aed16fc2927
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/81e21cb7bd1479bb5238e0004a7e0110452c610b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a60b5da05e318d9a364dbac38c347c7f24e625e7
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/cb469993b3a61a72653770856d37af616d72d05f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fd6a6c43f96b40a08a22ff62f08d194a49741c8a
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/connection.h",
            "fs/smb/server/smb2pdu.c",
            "fs/smb/server/smb_common.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0b1390cf2b6b91723b37c0909dd123f7a5eba1a7",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            },
            {
              "lessThan": "fd6a6c43f96b40a08a22ff62f08d194a49741c8a",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            },
            {
              "lessThan": "81e21cb7bd1479bb5238e0004a7e0110452c610b",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            },
            {
              "lessThan": "7fb8dbeb3f2868ae836ca12311d89aed16fc2927",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            },
            {
              "lessThan": "a60b5da05e318d9a364dbac38c347c7f24e625e7",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            },
            {
              "lessThan": "7e02cb30e8a1f5fc78cb10b220b06020e36d0bbe",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            },
            {
              "lessThan": "cb469993b3a61a72653770856d37af616d72d05f",
              "status": "affected",
              "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/connection.h",
            "fs/smb/server/smb2pdu.c",
            "fs/smb/server/smb_common.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.217",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.184",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.153",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.105",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.44",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: reject repeated SMB2 NEGOTIATE requests\n\nUnauthenticated client can send multiple successful SMB2 NEGOTIATE\nrequests on one connection before SESSION_SETUP. While the connection is\nin KSMBD_SESS_NEED_SETUP, smb2_handle_negotiate() accepts another\nSMB3.1.1 NEGOTIATE and overwrites conn-\u003epreauth_info with a new allocation.\nOnly the final allocation is freed when the connection is released, leaking\none object for every additional successful request.\n\nA repeated SMB2 NEGOTIATE after a dialect has been selected is a protocol\nviolation. MS-SMB2 section 3.3.5.4 requires the server to disconnect\nwithout replying in this case. Set the connection exiting when rejecting\nthe request, in addition to suppressing the response.\n\nReject SMB2 NEGOTIATE unless the connection is new or is waiting for the\nSMB2 NEGOTIATE that follows an SMB1 multi-protocol negotiate. Serialize\nboth SMB1 and SMB2 negotiation paths under conn-\u003esrv_mutex, since they\nupdate connection-wide dialect and negotiation state.\n\nMove the locking contract to ksmbd_smb_negotiate_common(), where the state\nand dialect are selected, and add ksmbd_conn_new() for consistent state\naccess."
    }
  ],
  "id": "CVE-2026-74494",
  "lastModified": "2026-08-23T13:16:44.870",
  "metrics": {},
  "published": "2026-08-15T13:17:54.353",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0b1390cf2b6b91723b37c0909dd123f7a5eba1a7"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7e02cb30e8a1f5fc78cb10b220b06020e36d0bbe"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7fb8dbeb3f2868ae836ca12311d89aed16fc2927"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/81e21cb7bd1479bb5238e0004a7e0110452c610b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a60b5da05e318d9a364dbac38c347c7f24e625e7"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/cb469993b3a61a72653770856d37af616d72d05f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fd6a6c43f96b40a08a22ff62f08d194a49741c8a"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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