Vulnerability-Lookup

GHSA-VPGG-8CCQ-GWHG

Vulnerability from github – Published: 2024-03-25 09:32 – Updated: 2024-11-05 18:31

Details

In the Linux kernel, the following vulnerability has been resolved:

i2c: i801: Don't generate an interrupt on bus reset

Now that the i2c-i801 driver supports interrupts, setting the KILL bit in a attempt to recover from a timed out transaction triggers an interrupt. Unfortunately, the interrupt handler (i801_isr) is not prepared for this situation and will try to process the interrupt as if it was signaling the end of a successful transaction. In the case of a block transaction, this can result in an out-of-range memory access.

This condition was reproduced several times by syzbot: https://syzkaller.appspot.com/bug?extid=ed71512d469895b5b34e https://syzkaller.appspot.com/bug?extid=8c8dedc0ba9e03f6c79e https://syzkaller.appspot.com/bug?extid=c8ff0b6d6c73d81b610e https://syzkaller.appspot.com/bug?extid=33f6c360821c399d69eb https://syzkaller.appspot.com/bug?extid=be15dc0b1933f04b043a https://syzkaller.appspot.com/bug?extid=b4d3fd1dfd53e90afd79

So disable interrupts while trying to reset the bus. Interrupts will be enabled again for the following transaction.

Severity

6.0 (Medium)


                  
                    CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2021-47153"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-125"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-03-25T09:15:09Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: i801: Don\u0027t generate an interrupt on bus reset\n\nNow that the i2c-i801 driver supports interrupts, setting the KILL bit\nin a attempt to recover from a timed out transaction triggers an\ninterrupt. Unfortunately, the interrupt handler (i801_isr) is not\nprepared for this situation and will try to process the interrupt as\nif it was signaling the end of a successful transaction. In the case\nof a block transaction, this can result in an out-of-range memory\naccess.\n\nThis condition was reproduced several times by syzbot:\nhttps://syzkaller.appspot.com/bug?extid=ed71512d469895b5b34e\nhttps://syzkaller.appspot.com/bug?extid=8c8dedc0ba9e03f6c79e\nhttps://syzkaller.appspot.com/bug?extid=c8ff0b6d6c73d81b610e\nhttps://syzkaller.appspot.com/bug?extid=33f6c360821c399d69eb\nhttps://syzkaller.appspot.com/bug?extid=be15dc0b1933f04b043a\nhttps://syzkaller.appspot.com/bug?extid=b4d3fd1dfd53e90afd79\n\nSo disable interrupts while trying to reset the bus. Interrupts will\nbe enabled again for the following transaction.",
  "id": "GHSA-vpgg-8ccq-gwhg",
  "modified": "2024-11-05T18:31:58Z",
  "published": "2024-03-25T09:32:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-47153"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/04cc05e3716ae31b17ecdab7bc55c8170def1b8b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/09c9e79f4c10cfb6b9e0e1b4dd355232e4b5a3b3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1f583d3813f204449037cd2acbfc09168171362a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b523feb7e8e44652f92f3babb953a976e7ccbbef"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c70e1ba2e7e65255a0ce004f531dd90dada97a8c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dfa8929e117b0228a7765f5c3f5988a4a028f3c6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e4d8716c3dcec47f1557024add24e1f3c09eb24b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f9469082126cebb7337db3992d143f5e4edfe629"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2021-47153 (GCVE-0-2021-47153)

Vulnerability from cvelistv5 – Published: 2024-03-25 09:07 – Updated: 2026-08-05 08:46

Title

i2c: i801: Don't generate an interrupt on bus reset

Summary

In the Linux kernel, the following vulnerability has been resolved: i2c: i801: Don't generate an interrupt on bus reset Now that the i2c-i801 driver supports interrupts, setting the KILL bit in a attempt to recover from a timed out transaction triggers an interrupt. Unfortunately, the interrupt handler (i801_isr) is not prepared for this situation and will try to process the interrupt as if it was signaling the end of a successful transaction. In the case of a block transaction, this can result in an out-of-range memory access. This condition was reproduced several times by syzbot: https://syzkaller.appspot.com/bug?extid=ed71512d469895b5b34e https://syzkaller.appspot.com/bug?extid=8c8dedc0ba9e03f6c79e https://syzkaller.appspot.com/bug?extid=c8ff0b6d6c73d81b610e https://syzkaller.appspot.com/bug?extid=33f6c360821c399d69eb https://syzkaller.appspot.com/bug?extid=be15dc0b1933f04b043a https://syzkaller.appspot.com/bug?extid=b4d3fd1dfd53e90afd79 So disable interrupts while trying to reset the bus. Interrupts will be enabled again for the following transaction.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

6 (Medium)


                        
                          CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2024-03-25 19:20 UTC

CWE

CWE-noinfo Not enough information

Assigner

Linux mitre root

References

8 references

URL	Tags
https://git.kernel.org/stable/c/f9469082126cebb73…
https://git.kernel.org/stable/c/09c9e79f4c10cfb6b…
https://git.kernel.org/stable/c/dfa8929e117b0228a…
https://git.kernel.org/stable/c/c70e1ba2e7e65255a…
https://git.kernel.org/stable/c/04cc05e3716ae31b1…
https://git.kernel.org/stable/c/b523feb7e8e44652f…
https://git.kernel.org/stable/c/1f583d3813f204449…
https://git.kernel.org/stable/c/e4d8716c3dcec47f1…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 636752bcb5177a301d0266270661581de8624828 , < f9469082126cebb7337db3992d143f5e4edfe629 (git) Affected: 636752bcb5177a301d0266270661581de8624828 , < 09c9e79f4c10cfb6b9e0e1b4dd355232e4b5a3b3 (git) Affected: 636752bcb5177a301d0266270661581de8624828 , < dfa8929e117b0228a7765f5c3f5988a4a028f3c6 (git) Affected: 636752bcb5177a301d0266270661581de8624828 , < c70e1ba2e7e65255a0ce004f531dd90dada97a8c (git) Affected: 636752bcb5177a301d0266270661581de8624828 , < 04cc05e3716ae31b17ecdab7bc55c8170def1b8b (git) Affected: 636752bcb5177a301d0266270661581de8624828 , < b523feb7e8e44652f92f3babb953a976e7ccbbef (git) Affected: 636752bcb5177a301d0266270661581de8624828 , < 1f583d3813f204449037cd2acbfc09168171362a (git) Affected: 636752bcb5177a301d0266270661581de8624828 , < e4d8716c3dcec47f1557024add24e1f3c09eb24b (git)
Linux	Linux	Affected: 3.6 Unaffected: 0 , < 3.6 (semver) Unaffected: 4.4.271 , ≤ 4.4.* (semver) Unaffected: 4.9.271 , ≤ 4.9.* (semver) Unaffected: 4.14.235 , ≤ 4.14.* (semver) Unaffected: 4.19.193 , ≤ 4.19.* (semver) Unaffected: 5.4.124 , ≤ 5.4.* (semver) Unaffected: 5.10.42 , ≤ 5.10.* (semver) Unaffected: 5.12.9 , ≤ 5.12.* (semver) Unaffected: 5.13 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "LOCAL",
              "availabilityImpact": "HIGH",
              "baseScore": 6,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "HIGH",
              "integrityImpact": "NONE",
              "privilegesRequired": "HIGH",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2021-47153",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2024-03-25T19:20:15.941507Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "description": "CWE-noinfo Not enough information",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2024-11-05T16:55:32.968Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-04T05:24:39.990Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/f9469082126cebb7337db3992d143f5e4edfe629"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/09c9e79f4c10cfb6b9e0e1b4dd355232e4b5a3b3"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/dfa8929e117b0228a7765f5c3f5988a4a028f3c6"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/c70e1ba2e7e65255a0ce004f531dd90dada97a8c"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/04cc05e3716ae31b17ecdab7bc55c8170def1b8b"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/b523feb7e8e44652f92f3babb953a976e7ccbbef"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/1f583d3813f204449037cd2acbfc09168171362a"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/e4d8716c3dcec47f1557024add24e1f3c09eb24b"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/i2c/busses/i2c-i801.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f9469082126cebb7337db3992d143f5e4edfe629",
              "status": "affected",
              "version": "636752bcb5177a301d0266270661581de8624828",
              "versionType": "git"
            },
            {
              "lessThan": "09c9e79f4c10cfb6b9e0e1b4dd355232e4b5a3b3",
              "status": "affected",
              "version": "636752bcb5177a301d0266270661581de8624828",
              "versionType": "git"
            },
            {
              "lessThan": "dfa8929e117b0228a7765f5c3f5988a4a028f3c6",
              "status": "affected",
              "version": "636752bcb5177a301d0266270661581de8624828",
              "versionType": "git"
            },
            {
              "lessThan": "c70e1ba2e7e65255a0ce004f531dd90dada97a8c",
              "status": "affected",
              "version": "636752bcb5177a301d0266270661581de8624828",
              "versionType": "git"
            },
            {
              "lessThan": "04cc05e3716ae31b17ecdab7bc55c8170def1b8b",
              "status": "affected",
              "version": "636752bcb5177a301d0266270661581de8624828",
              "versionType": "git"
            },
            {
              "lessThan": "b523feb7e8e44652f92f3babb953a976e7ccbbef",
              "status": "affected",
              "version": "636752bcb5177a301d0266270661581de8624828",
              "versionType": "git"
            },
            {
              "lessThan": "1f583d3813f204449037cd2acbfc09168171362a",
              "status": "affected",
              "version": "636752bcb5177a301d0266270661581de8624828",
              "versionType": "git"
            },
            {
              "lessThan": "e4d8716c3dcec47f1557024add24e1f3c09eb24b",
              "status": "affected",
              "version": "636752bcb5177a301d0266270661581de8624828",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/i2c/busses/i2c-i801.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.6"
            },
            {
              "lessThan": "3.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "4.4.*",
              "status": "unaffected",
              "version": "4.4.271",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "4.9.*",
              "status": "unaffected",
              "version": "4.9.271",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "4.14.*",
              "status": "unaffected",
              "version": "4.14.235",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "4.19.*",
              "status": "unaffected",
              "version": "4.19.193",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.4.*",
              "status": "unaffected",
              "version": "5.4.124",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.12.*",
              "status": "unaffected",
              "version": "5.12.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "5.13",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "4.4.271",
                  "versionStartIncluding": "3.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "4.9.271",
                  "versionStartIncluding": "3.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "4.14.235",
                  "versionStartIncluding": "3.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "4.19.193",
                  "versionStartIncluding": "3.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.4.124",
                  "versionStartIncluding": "3.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.42",
                  "versionStartIncluding": "3.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.12.9",
                  "versionStartIncluding": "3.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.13",
                  "versionStartIncluding": "3.6",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: i801: Don\u0027t generate an interrupt on bus reset\n\nNow that the i2c-i801 driver supports interrupts, setting the KILL bit\nin a attempt to recover from a timed out transaction triggers an\ninterrupt. Unfortunately, the interrupt handler (i801_isr) is not\nprepared for this situation and will try to process the interrupt as\nif it was signaling the end of a successful transaction. In the case\nof a block transaction, this can result in an out-of-range memory\naccess.\n\nThis condition was reproduced several times by syzbot:\nhttps://syzkaller.appspot.com/bug?extid=ed71512d469895b5b34e\nhttps://syzkaller.appspot.com/bug?extid=8c8dedc0ba9e03f6c79e\nhttps://syzkaller.appspot.com/bug?extid=c8ff0b6d6c73d81b610e\nhttps://syzkaller.appspot.com/bug?extid=33f6c360821c399d69eb\nhttps://syzkaller.appspot.com/bug?extid=be15dc0b1933f04b043a\nhttps://syzkaller.appspot.com/bug?extid=b4d3fd1dfd53e90afd79\n\nSo disable interrupts while trying to reset the bus. Interrupts will\nbe enabled again for the following transaction."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerable path is reached locally via /dev/i2c-* I2C_SMBUS ioctls into i801_access \u2192 i801_block_transaction_byte_by_byte \u2192 i801_check_post; it is not reachable from network packet processing or physical SMBus injection.\nAC:L - An attacker who can open the adapter can issue block SMBus transactions and force wait_event_timeout to expire (including via I2C_TIMEOUT), reliably hitting the KILL path that leaves INTREN set; syzbot reproduced this repeatedly with no attacker-uncontrollable race required.\nPR:L - i2cdev_open() performs no capability check\u2014access is only DAC on /dev/i2c-*. On realistic worst-case deployments (i2c group or similarly relaxed permissions on developer/embedded/x86 systems with Intel PCH SMBus), a non-root local user can reach the path.\nUI:N - The attacker opens the device and issues the ioctls themselves; no separate victim action is required.\nS:U - Impact is ordinary in-kernel stack/memory corruption within the host kernel authority, not a VM escape, IOMMU bypass, or other cross-boundary breakout.\nC:H - The ISR performs out-of-range accesses on the block buffer (KASAN OOB reads) and related crashes show use-after-free of that buffer; this class of memory corruption is scored as enabling high confidentiality impact under the higher-severity rule.\nI:H - Syzbot also hit out-of-bounds/use-after-free writes in i801_isr_byte_done for the same root cause (KILL-generated interrupt while INTREN remains set), giving stack/heap corruption exploitable for control-flow hijacking.\nA:H - The memory-safety failure reliably produces kernel oops/KASAN reports and can panic the system, which is Availability High under kernel CVSS guidance."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T08:46:21.812Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f9469082126cebb7337db3992d143f5e4edfe629"
        },
        {
          "url": "https://git.kernel.org/stable/c/09c9e79f4c10cfb6b9e0e1b4dd355232e4b5a3b3"
        },
        {
          "url": "https://git.kernel.org/stable/c/dfa8929e117b0228a7765f5c3f5988a4a028f3c6"
        },
        {
          "url": "https://git.kernel.org/stable/c/c70e1ba2e7e65255a0ce004f531dd90dada97a8c"
        },
        {
          "url": "https://git.kernel.org/stable/c/04cc05e3716ae31b17ecdab7bc55c8170def1b8b"
        },
        {
          "url": "https://git.kernel.org/stable/c/b523feb7e8e44652f92f3babb953a976e7ccbbef"
        },
        {
          "url": "https://git.kernel.org/stable/c/1f583d3813f204449037cd2acbfc09168171362a"
        },
        {
          "url": "https://git.kernel.org/stable/c/e4d8716c3dcec47f1557024add24e1f3c09eb24b"
        }
      ],
      "title": "i2c: i801: Don\u0027t generate an interrupt on bus reset",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2021-47153",
    "datePublished": "2024-03-25T09:07:47.873Z",
    "dateReserved": "2024-03-04T18:12:48.846Z",
    "dateUpdated": "2026-08-05T08:46:21.812Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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.