CVE-2026-74494 (GCVE-0-2026-74494)
Vulnerability from cvelistv5
Published
2026-08-15 12:27
Modified
2026-08-23 12:47
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
Impacted products
Vendor Product Version
Linux Linux Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "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"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.217",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.184",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.153",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.105",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.44",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.8",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-23T12:47:27.752Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0b1390cf2b6b91723b37c0909dd123f7a5eba1a7"
        },
        {
          "url": "https://git.kernel.org/stable/c/fd6a6c43f96b40a08a22ff62f08d194a49741c8a"
        },
        {
          "url": "https://git.kernel.org/stable/c/81e21cb7bd1479bb5238e0004a7e0110452c610b"
        },
        {
          "url": "https://git.kernel.org/stable/c/7fb8dbeb3f2868ae836ca12311d89aed16fc2927"
        },
        {
          "url": "https://git.kernel.org/stable/c/a60b5da05e318d9a364dbac38c347c7f24e625e7"
        },
        {
          "url": "https://git.kernel.org/stable/c/7e02cb30e8a1f5fc78cb10b220b06020e36d0bbe"
        },
        {
          "url": "https://git.kernel.org/stable/c/cb469993b3a61a72653770856d37af616d72d05f"
        }
      ],
      "title": "ksmbd: reject repeated SMB2 NEGOTIATE requests",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74494",
    "datePublished": "2026-08-15T12:27:22.609Z",
    "dateReserved": "2026-08-15T05:44:03.906Z",
    "dateUpdated": "2026-08-23T12:47:27.752Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.