CVE-2015-6526 (GCVE-0-2015-6526)

Vulnerability from cvelistv5 – Published: 2015-08-31 20:00 – Updated: 2024-08-06 07:22
VLAI
Summary
The perf_callchain_user_64 function in arch/powerpc/perf/callchain.c in the Linux kernel before 4.0.2 on ppc64 platforms allows local users to cause a denial of service (infinite loop) via a deep 64-bit userspace backtrace.
Severity
No CVSS data available.
CWE
  • n/a
Assigner
mitre CNA under the mitre root
CNA scorecard E 28/100 over 2359 records in the last 180 days details
Date Public
2015-05-06 00:00
Show details on NVD website

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-06T07:22:22.199Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "https://github.com/torvalds/linux/commit/9a5cbce421a283e6aea3c4007f141735bf9da8c3"
          },
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html"
          },
          {
            "name": "USN-2760-1",
            "tags": [
              "vendor-advisory",
              "x_refsource_UBUNTU",
              "x_transferred"
            ],
            "url": "http://www.ubuntu.com/usn/USN-2760-1"
          },
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1218454"
          },
          {
            "name": "USN-2759-1",
            "tags": [
              "vendor-advisory",
              "x_refsource_UBUNTU",
              "x_transferred"
            ],
            "url": "http://www.ubuntu.com/usn/USN-2759-1"
          },
          {
            "name": "[oss-security] 20150818 CVE request - Linux kernel - perf on ppp64 - unbounded checks in perf_callchain_user_64 denial of service.",
            "tags": [
              "mailing-list",
              "x_refsource_MLIST",
              "x_transferred"
            ],
            "url": "http://www.openwall.com/lists/oss-security/2015/08/18/4"
          },
          {
            "name": "1033728",
            "tags": [
              "vdb-entry",
              "x_refsource_SECTRACK",
              "x_transferred"
            ],
            "url": "http://www.securitytracker.com/id/1033728"
          },
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9a5cbce421a283e6aea3c4007f141735bf9da8c3"
          },
          {
            "name": "76401",
            "tags": [
              "vdb-entry",
              "x_refsource_BID",
              "x_transferred"
            ],
            "url": "http://www.securityfocus.com/bid/76401"
          },
          {
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.0.2"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "n/a",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ],
      "datePublic": "2015-05-06T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "The perf_callchain_user_64 function in arch/powerpc/perf/callchain.c in the Linux kernel before 4.0.2 on ppc64 platforms allows local users to cause a denial of service (infinite loop) via a deep 64-bit userspace backtrace."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "n/a",
              "lang": "en",
              "type": "text"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2016-12-06T18:57:01.000Z",
        "orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
        "shortName": "mitre"
      },
      "references": [
        {
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/torvalds/linux/commit/9a5cbce421a283e6aea3c4007f141735bf9da8c3"
        },
        {
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html"
        },
        {
          "name": "USN-2760-1",
          "tags": [
            "vendor-advisory",
            "x_refsource_UBUNTU"
          ],
          "url": "http://www.ubuntu.com/usn/USN-2760-1"
        },
        {
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1218454"
        },
        {
          "name": "USN-2759-1",
          "tags": [
            "vendor-advisory",
            "x_refsource_UBUNTU"
          ],
          "url": "http://www.ubuntu.com/usn/USN-2759-1"
        },
        {
          "name": "[oss-security] 20150818 CVE request - Linux kernel - perf on ppp64 - unbounded checks in perf_callchain_user_64 denial of service.",
          "tags": [
            "mailing-list",
            "x_refsource_MLIST"
          ],
          "url": "http://www.openwall.com/lists/oss-security/2015/08/18/4"
        },
        {
          "name": "1033728",
          "tags": [
            "vdb-entry",
            "x_refsource_SECTRACK"
          ],
          "url": "http://www.securitytracker.com/id/1033728"
        },
        {
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9a5cbce421a283e6aea3c4007f141735bf9da8c3"
        },
        {
          "name": "76401",
          "tags": [
            "vdb-entry",
            "x_refsource_BID"
          ],
          "url": "http://www.securityfocus.com/bid/76401"
        },
        {
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.0.2"
        }
      ],
      "x_legacyV4Record": {
        "CVE_data_meta": {
          "ASSIGNER": "cve@mitre.org",
          "ID": "CVE-2015-6526",
          "STATE": "PUBLIC"
        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
                  "product_data": [
                    {
                      "product_name": "n/a",
                      "version": {
                        "version_data": [
                          {
                            "version_value": "n/a"
                          }
                        ]
                      }
                    }
                  ]
                },
                "vendor_name": "n/a"
              }
            ]
          }
        },
        "data_format": "MITRE",
        "data_type": "CVE",
        "data_version": "4.0",
        "description": {
          "description_data": [
            {
              "lang": "eng",
              "value": "The perf_callchain_user_64 function in arch/powerpc/perf/callchain.c in the Linux kernel before 4.0.2 on ppc64 platforms allows local users to cause a denial of service (infinite loop) via a deep 64-bit userspace backtrace."
            }
          ]
        },
        "problemtype": {
          "problemtype_data": [
            {
              "description": [
                {
                  "lang": "eng",
                  "value": "n/a"
                }
              ]
            }
          ]
        },
        "references": {
          "reference_data": [
            {
              "name": "https://github.com/torvalds/linux/commit/9a5cbce421a283e6aea3c4007f141735bf9da8c3",
              "refsource": "CONFIRM",
              "url": "https://github.com/torvalds/linux/commit/9a5cbce421a283e6aea3c4007f141735bf9da8c3"
            },
            {
              "name": "http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html",
              "refsource": "CONFIRM",
              "url": "http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html"
            },
            {
              "name": "USN-2760-1",
              "refsource": "UBUNTU",
              "url": "http://www.ubuntu.com/usn/USN-2760-1"
            },
            {
              "name": "https://bugzilla.redhat.com/show_bug.cgi?id=1218454",
              "refsource": "CONFIRM",
              "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1218454"
            },
            {
              "name": "USN-2759-1",
              "refsource": "UBUNTU",
              "url": "http://www.ubuntu.com/usn/USN-2759-1"
            },
            {
              "name": "[oss-security] 20150818 CVE request - Linux kernel - perf on ppp64 - unbounded checks in perf_callchain_user_64 denial of service.",
              "refsource": "MLIST",
              "url": "http://www.openwall.com/lists/oss-security/2015/08/18/4"
            },
            {
              "name": "1033728",
              "refsource": "SECTRACK",
              "url": "http://www.securitytracker.com/id/1033728"
            },
            {
              "name": "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9a5cbce421a283e6aea3c4007f141735bf9da8c3",
              "refsource": "CONFIRM",
              "url": "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9a5cbce421a283e6aea3c4007f141735bf9da8c3"
            },
            {
              "name": "76401",
              "refsource": "BID",
              "url": "http://www.securityfocus.com/bid/76401"
            },
            {
              "name": "http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.0.2",
              "refsource": "CONFIRM",
              "url": "http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.0.2"
            }
          ]
        }
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
    "assignerShortName": "mitre",
    "cveId": "CVE-2015-6526",
    "datePublished": "2015-08-31T20:00:00.000Z",
    "dateReserved": "2015-08-20T00:00:00.000Z",
    "dateUpdated": "2024-08-06T07:22:22.199Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2015-6526",
      "date": "2026-10-22",
      "epss": "0.00393",
      "percentile": "0.32274"
    },
    "fkie_nvd": {
      "configurations": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "matchCriteriaId": "D460F925-66B4-4BED-BD3B-91A8C60B8AC4",
                  "versionEndIncluding": "4.0.1",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "The perf_callchain_user_64 function in arch/powerpc/perf/callchain.c in the Linux kernel before 4.0.2 on ppc64 platforms allows local users to cause a denial of service (infinite loop) via a deep 64-bit userspace backtrace."
        },
        {
          "lang": "es",
          "value": "Vulnerabilidad en la funci\u00f3n perf_callchain_user_64 en arch/powerpc/perf/callchain.c en el kernel de Linux en versiones anteriores a 4.0.2 sobre plataformas ppc64, permite a usuarios locales causar una denegaci\u00f3n de servicio (bucle infinito) a trav\u00e9s de una traza inversa profunda en el espacio de usuario de 64-bit."
        }
      ],
      "id": "CVE-2015-6526",
      "lastModified": "2024-11-21T02:35:09.780",
      "metrics": {
        "cvssMetricV2": [
          {
            "acInsufInfo": false,
            "baseSeverity": "MEDIUM",
            "cvssData": {
              "accessComplexity": "LOW",
              "accessVector": "LOCAL",
              "authentication": "NONE",
              "availabilityImpact": "COMPLETE",
              "baseScore": 4.9,
              "confidentialityImpact": "NONE",
              "integrityImpact": "NONE",
              "vectorString": "AV:L/AC:L/Au:N/C:N/I:N/A:C",
              "version": "2.0"
            },
            "exploitabilityScore": 3.9,
            "impactScore": 6.9,
            "obtainAllPrivilege": false,
            "obtainOtherPrivilege": false,
            "obtainUserPrivilege": false,
            "source": "nvd@nist.gov",
            "type": "Primary",
            "userInteractionRequired": false
          }
        ]
      },
      "published": "2015-08-31T20:59:07.357",
      "references": [
        {
          "source": "cve@mitre.org",
          "url": "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9a5cbce421a283e6aea3c4007f141735bf9da8c3"
        },
        {
          "source": "cve@mitre.org",
          "url": "http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.0.2"
        },
        {
          "source": "cve@mitre.org",
          "url": "http://www.openwall.com/lists/oss-security/2015/08/18/4"
        },
        {
          "source": "cve@mitre.org",
          "url": "http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html"
        },
        {
          "source": "cve@mitre.org",
          "url": "http://www.securityfocus.com/bid/76401"
        },
        {
          "source": "cve@mitre.org",
          "url": "http://www.securitytracker.com/id/1033728"
        },
        {
          "source": "cve@mitre.org",
          "url": "http://www.ubuntu.com/usn/USN-2759-1"
        },
        {
          "source": "cve@mitre.org",
          "url": "http://www.ubuntu.com/usn/USN-2760-1"
        },
        {
          "source": "cve@mitre.org",
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1218454"
        },
        {
          "source": "cve@mitre.org",
          "url": "https://github.com/torvalds/linux/commit/9a5cbce421a283e6aea3c4007f141735bf9da8c3"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9a5cbce421a283e6aea3c4007f141735bf9da8c3"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.0.2"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "http://www.openwall.com/lists/oss-security/2015/08/18/4"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "http://www.securityfocus.com/bid/76401"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "http://www.securitytracker.com/id/1033728"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "http://www.ubuntu.com/usn/USN-2759-1"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "http://www.ubuntu.com/usn/USN-2760-1"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1218454"
        },
        {
          "source": "af854a3a-2127-422b-91ae-364da2661108",
          "url": "https://github.com/torvalds/linux/commit/9a5cbce421a283e6aea3c4007f141735bf9da8c3"
        }
      ],
      "sourceIdentifier": "cve@mitre.org",
      "vulnStatus": "Modified",
      "weaknesses": [
        {
          "description": [
            {
              "lang": "en",
              "value": "CWE-399"
            }
          ],
          "source": "nvd@nist.gov",
          "type": "Primary"
        }
      ]
    },
    "nvd": {
      "cve": {
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "D460F925-66B4-4BED-BD3B-91A8C60B8AC4",
                    "versionEndIncluding": "4.0.1",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "The perf_callchain_user_64 function in arch/powerpc/perf/callchain.c in the Linux kernel before 4.0.2 on ppc64 platforms allows local users to cause a denial of service (infinite loop) via a deep 64-bit userspace backtrace."
          },
          {
            "lang": "es",
            "value": "Vulnerabilidad en la funci\u00f3n perf_callchain_user_64 en arch/powerpc/perf/callchain.c en el kernel de Linux en versiones anteriores a 4.0.2 sobre plataformas ppc64, permite a usuarios locales causar una denegaci\u00f3n de servicio (bucle infinito) a trav\u00e9s de una traza inversa profunda en el espacio de usuario de 64-bit."
          }
        ],
        "id": "CVE-2015-6526",
        "lastModified": "2026-05-06T22:30:45.220",
        "metrics": {
          "cvssMetricV2": [
            {
              "acInsufInfo": false,
              "baseSeverity": "MEDIUM",
              "cvssData": {
                "accessComplexity": "LOW",
                "accessVector": "LOCAL",
                "authentication": "NONE",
                "availabilityImpact": "COMPLETE",
                "baseScore": 4.9,
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "vectorString": "AV:L/AC:L/Au:N/C:N/I:N/A:C",
                "version": "2.0"
              },
              "exploitabilityScore": 3.9,
              "impactScore": 6.9,
              "obtainAllPrivilege": false,
              "obtainOtherPrivilege": false,
              "obtainUserPrivilege": false,
              "source": "nvd@nist.gov",
              "type": "Primary",
              "userInteractionRequired": false
            }
          ]
        },
        "published": "2015-08-31T20:59:07.357",
        "references": [
          {
            "source": "cve@mitre.org",
            "url": "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9a5cbce421a283e6aea3c4007f141735bf9da8c3"
          },
          {
            "source": "cve@mitre.org",
            "url": "http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.0.2"
          },
          {
            "source": "cve@mitre.org",
            "url": "http://www.openwall.com/lists/oss-security/2015/08/18/4"
          },
          {
            "source": "cve@mitre.org",
            "url": "http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html"
          },
          {
            "source": "cve@mitre.org",
            "url": "http://www.securityfocus.com/bid/76401"
          },
          {
            "source": "cve@mitre.org",
            "url": "http://www.securitytracker.com/id/1033728"
          },
          {
            "source": "cve@mitre.org",
            "url": "http://www.ubuntu.com/usn/USN-2759-1"
          },
          {
            "source": "cve@mitre.org",
            "url": "http://www.ubuntu.com/usn/USN-2760-1"
          },
          {
            "source": "cve@mitre.org",
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1218454"
          },
          {
            "source": "cve@mitre.org",
            "url": "https://github.com/torvalds/linux/commit/9a5cbce421a283e6aea3c4007f141735bf9da8c3"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "url": "http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9a5cbce421a283e6aea3c4007f141735bf9da8c3"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "url": "http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.0.2"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "url": "http://www.openwall.com/lists/oss-security/2015/08/18/4"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "url": "http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "url": "http://www.securityfocus.com/bid/76401"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "url": "http://www.securitytracker.com/id/1033728"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "url": "http://www.ubuntu.com/usn/USN-2759-1"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "url": "http://www.ubuntu.com/usn/USN-2760-1"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1218454"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "url": "https://github.com/torvalds/linux/commit/9a5cbce421a283e6aea3c4007f141735bf9da8c3"
          }
        ],
        "sourceIdentifier": "cve@mitre.org",
        "vulnStatus": "Modified",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-399"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2025-11-21T12:15:31+00:00",
      "cve": "CVE-2015-6526",
      "id": "CVE-2015-6526",
      "initial_release_date": "2015-04-13T00:00:00+00:00",
      "product_status:fixed": "544",
      "product_status:known_not_affected": "39",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: perf on ppc64 can loop forever getting userlevel stacktraces",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2015/cve-2015-6526.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-07-26T01:12:40Z",
      "cve": "CVE-2015-6526",
      "id": "CVE-2015-6526",
      "initial_release_date": "2023-02-15T05:15:17Z",
      "product_status:known_not_affected": "30",
      "product_status:recommended": "12",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2015-6526",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2015-6526.json",
      "version": "10"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.


Loading…

Loading…

Loading…

Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
Events included in the timeline

Loading timeline…


    Loading…

    Loading…

    Loading…

    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.