{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "fad4161b5cd01a24202234976ebbb133f7adc0b5"
            },
            {
              "fixed": "745a535461bbb90a56d9357573c9f97a5c12abe1"
            },
            {
              "fixed": "dd577cb55588ec3fbc66af3621280306601c4192"
            },
            {
              "fixed": "dd53414e301beb915fe672dc4c4a51bafb917604"
            },
            {
              "fixed": "269c800a7a7e363459291885b35f7bc72e231ed6"
            },
            {
              "fixed": "6c8c44e6553b9f072f62d9875e567766eb293162"
            },
            {
              "fixed": "ad0057fb91218914d6c98268718ceb9d59b388e1"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.15.0"
            },
            {
              "fixed": "6.6.136"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.83"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.24"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "6.19.14"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.20.0"
            },
            {
              "fixed": "7.0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31610.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix mechToken leak when SPNEGO decode fails after token alloc\n\nThe kernel ASN.1 BER decoder calls action callbacks incrementally as it\nwalks the input.  When ksmbd_decode_negTokenInit() reaches the mechToken\n[2] OCTET STRING element, ksmbd_neg_token_alloc() allocates\nconn-\u003emechToken immediately via kmemdup_nul().  If a later element in\nthe same blob is malformed, then the decoder will return nonzero after\nthe allocation is already live.  This could happen if mechListMIC [3]\noverrunse the enclosing SEQUENCE.\n\ndecode_negotiation_token() then sets conn-\u003euse_spnego = false because\nboth the negTokenInit and negTokenTarg grammars failed.  The cleanup at\nthe bottom of smb2_sess_setup() is gated on use_spnego:\n\n\tif (conn-\u003euse_spnego \u0026\u0026 conn-\u003emechToken) {\n\t\tkfree(conn-\u003emechToken);\n\t\tconn-\u003emechToken = NULL;\n\t}\n\nso the kfree is skipped, causing the mechToken to never be freed.\n\nThis codepath is reachable pre-authentication, so untrusted clients can\ncause slow memory leaks on a server without even being properly\nauthenticated.\n\nFix this up by not checking check for use_spnego, as it's not required,\nso the memory will always be properly freed.  At the same time, always\nfree the memory in ksmbd_conn_free() incase some other failure path\nforgot to free it.",
  "id": "CVE-2026-31610",
  "modified": "2026-07-15T01:49:14.391259745Z",
  "published": "2026-04-24T14:42:31.471Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/269c800a7a7e363459291885b35f7bc72e231ed6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6c8c44e6553b9f072f62d9875e567766eb293162"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/745a535461bbb90a56d9357573c9f97a5c12abe1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ad0057fb91218914d6c98268718ceb9d59b388e1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dd53414e301beb915fe672dc4c4a51bafb917604"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dd577cb55588ec3fbc66af3621280306601c4192"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31610.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31610"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "summary": "ksmbd: fix mechToken leak when SPNEGO decode fails after token alloc"
}