Vulnerability-Lookup

CVE-2021-21405 (GCVE-0-2021-21405)

Vulnerability from cvelistv5 – Published: 2021-04-15 21:35 – Updated: 2024-08-03 18:09

Title

BLS Signature "Malleability"

Summary

Lotus is an Implementation of the Filecoin protocol written in Go. BLS signature validation in lotus uses blst library method VerifyCompressed. This method accepts signatures in 2 forms: "serialized", and "compressed", meaning that BLS signatures can be provided as either of 2 unique byte arrays. Lotus block validation functions perform a uniqueness check on provided blocks. Two blocks are considered distinct if the CIDs of their blockheader do not match. The CID method for blockheader includes the BlockSig of the block. The result of these issues is that it would be possible to punish miners for valid blocks, as there are two different valid block CIDs available for each block, even though this must be unique. By switching from the go based `blst` bindings over to the bindings in `filecoin-ffi`, the code paths now ensure that all signatures are compressed by size and the way they are deserialized. This happened in https://github.com/filecoin-project/lotus/pull/5393.

Severity

5.9 (Medium)


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

CWE

CWE-347 - Improper Verification of Cryptographic Signature

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7836 records in the last 180 days details

References

3 references

URL	Tags
https://github.com/filecoin-project/lotus/securit…	x_refsource_CONFIRM
https://github.com/filecoin-project/lotus/pull/5393	x_refsource_MISC
https://gist.github.com/wadeAlexC/2490d522e81a796…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
filecoin-project	lotus	Affected: < 1.5.0	guessed

Show details on NVD website

JSON

To clipboard

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        "published": "2021-04-15T22:15:11.967",
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    "redhat_vex": {
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      "cve": "CVE-2021-21405",
      "id": "CVE-2021-21405",
      "initial_release_date": "2021-01-01T00:00:00+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "BLS Signature \"Malleability\"",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-21405.json",
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}

FKIE_CVE-2021-21405

Vulnerability from fkie_nvd - Published: 2021-04-15 22:15 - Updated: 2026-06-17 03:35

Severity

5.9 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Summary

References

URL	Tags
security-advisories@github.com	https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754	Exploit, Third Party Advisory
security-advisories@github.com	https://github.com/filecoin-project/lotus/pull/5393	Patch, Third Party Advisory
security-advisories@github.com	https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvh	Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108	https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754	Exploit, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108	https://github.com/filecoin-project/lotus/pull/5393	Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108	https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvh	Patch, Third Party Advisory

Impacted products

	Vendor	Product	Version
	filecoin	lotus	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "lotus",
          "vendor": "filecoin-project",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.5.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
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            {
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              "matchCriteriaId": "2E70B8AC-AD64-4FD9-9EDE-EB9C83587B69",
              "versionEndExcluding": "1.5.0",
              "vulnerable": true
            }
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          "negate": false,
          "operator": "OR"
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    {
      "lang": "en",
      "value": "Lotus is an Implementation of the Filecoin protocol written in Go. BLS signature validation in lotus uses blst library method VerifyCompressed. This method accepts signatures in 2 forms: \"serialized\", and \"compressed\", meaning that BLS signatures can be provided as either of 2 unique byte arrays. Lotus block validation functions perform a uniqueness check on provided blocks. Two blocks are considered distinct if the CIDs of their blockheader do not match. The CID method for blockheader includes the BlockSig of the block. The result of these issues is that it would be possible to punish miners for valid blocks, as there are two different valid block CIDs available for each block, even though this must be unique. By switching from the go based `blst` bindings over to the bindings in `filecoin-ffi`, the code paths now ensure that all signatures are compressed by size and the way they are deserialized. This happened in https://github.com/filecoin-project/lotus/pull/5393."
    },
    {
      "lang": "es",
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    }
  ],
  "id": "CVE-2021-21405",
  "lastModified": "2026-06-17T03:35:30.130",
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        "source": "security-advisories@github.com",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-04-15T22:15:11.967",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "url": "https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/filecoin-project/lotus/pull/5393"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvh"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "url": "https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/filecoin-project/lotus/pull/5393"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ],
      "url": "https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvh"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-347"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-4G52-PQCJ-PHVH

Vulnerability from github – Published: 2021-05-21 16:23 – Updated: 2021-05-20 20:51

Summary

BLS Signature "Malleability"

Details

Impact

BLS signature validation in lotus uses blst library method VerifyCompressed. This method accepts signatures in 2 forms - "serialized", and "compressed", meaning that BLS signatures can be provided as either of 2 unique byte arrays.
Lotus block validation functions perform a uniqueness check on provided blocks. Two blocks are considered distinct if the CIDs of their blockheader do not match. The CID method for blockheader includes the BlockSig of the block.

The result of these issues is that it would be possible to punish miners for valid blocks, as there are two different valid block CIDs available for each block, even though this must be unique.

Patches

By switching from the go based blst bindings over to the bindings in filecoin-ffi, the code paths now ensure that all signatures are compressed by size and the way they are deserialized. This happened in https://github.com/filecoin-project/lotus/pull/5393

References

Original POC: https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754

Severity

5.9 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/filecoin-project/lotus"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.5.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-21405"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-347"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-05-20T20:51:00Z",
    "nvd_published_at": "2021-04-15T22:15:00Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\n1. BLS signature validation in lotus uses blst library method VerifyCompressed. This method accepts signatures in 2 forms - \"serialized\", and \"compressed\", meaning that BLS signatures can be provided as either of 2 unique byte arrays.\n2. Lotus block validation functions perform a uniqueness check on provided blocks. Two blocks are considered distinct if the CIDs of their blockheader do not match. The CID method for blockheader includes the BlockSig of the block.\n\nThe result of these issues is that it would be possible to punish miners for valid blocks, as there are two different valid block CIDs available for each block, even though this must be unique.\n\n### Patches\n\nBy switching from the go based `blst` bindings over to the bindings in `filecoin-ffi`, the code paths now ensure that all signatures are compressed by size and the way they are deserialized.\nThis happened in https://github.com/filecoin-project/lotus/pull/5393\n\n\n### References\n\n- Original POC: https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754",
  "id": "GHSA-4g52-pqcj-phvh",
  "modified": "2021-05-20T20:51:00Z",
  "published": "2021-05-21T16:23:43Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21405"
    },
    {
      "type": "WEB",
      "url": "https://github.com/filecoin-project/lotus/pull/5393"
    },
    {
      "type": "WEB",
      "url": "https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "BLS Signature \"Malleability\""
}

GSD-2021-21405

Vulnerability from gsd - Updated: 2023-12-13 01:23

Details

Aliases

CVE-2021-21405

Aliases

CVE-2021-21405

JSON

To clipboard

{
  "GSD": {
    "alias": "CVE-2021-21405",
    "description": "Lotus is an Implementation of the Filecoin protocol written in Go. BLS signature validation in lotus uses blst library method VerifyCompressed. This method accepts signatures in 2 forms: \"serialized\", and \"compressed\", meaning that BLS signatures can be provided as either of 2 unique byte arrays. Lotus block validation functions perform a uniqueness check on provided blocks. Two blocks are considered distinct if the CIDs of their blockheader do not match. The CID method for blockheader includes the BlockSig of the block. The result of these issues is that it would be possible to punish miners for valid blocks, as there are two different valid block CIDs available for each block, even though this must be unique. By switching from the go based `blst` bindings over to the bindings in `filecoin-ffi`, the code paths now ensure that all signatures are compressed by size and the way they are deserialized. This happened in https://github.com/filecoin-project/lotus/pull/5393.",
    "id": "GSD-2021-21405"
  },
  "gsd": {
    "metadata": {
      "exploitCode": "unknown",
      "remediation": "unknown",
      "reportConfidence": "confirmed",
      "type": "vulnerability"
    },
    "osvSchema": {
      "aliases": [
        "CVE-2021-21405"
      ],
      "details": "Lotus is an Implementation of the Filecoin protocol written in Go. BLS signature validation in lotus uses blst library method VerifyCompressed. This method accepts signatures in 2 forms: \"serialized\", and \"compressed\", meaning that BLS signatures can be provided as either of 2 unique byte arrays. Lotus block validation functions perform a uniqueness check on provided blocks. Two blocks are considered distinct if the CIDs of their blockheader do not match. The CID method for blockheader includes the BlockSig of the block. The result of these issues is that it would be possible to punish miners for valid blocks, as there are two different valid block CIDs available for each block, even though this must be unique. By switching from the go based `blst` bindings over to the bindings in `filecoin-ffi`, the code paths now ensure that all signatures are compressed by size and the way they are deserialized. This happened in https://github.com/filecoin-project/lotus/pull/5393.",
      "id": "GSD-2021-21405",
      "modified": "2023-12-13T01:23:11.116875Z",
      "schema_version": "1.4.0"
    }
  },
  "namespaces": {
    "cve.org": {
      "CVE_data_meta": {
        "ASSIGNER": "security-advisories@github.com",
        "ID": "CVE-2021-21405",
        "STATE": "PUBLIC",
        "TITLE": "BLS Signature \"Malleability\""
      },
      "affects": {
        "vendor": {
          "vendor_data": [
            {
              "product": {
                "product_data": [
                  {
                    "product_name": "lotus",
                    "version": {
                      "version_data": [
                        {
                          "version_value": "\u003c 1.5.0"
                        }
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                    }
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            "lang": "eng",
            "value": "Lotus is an Implementation of the Filecoin protocol written in Go. BLS signature validation in lotus uses blst library method VerifyCompressed. This method accepts signatures in 2 forms: \"serialized\", and \"compressed\", meaning that BLS signatures can be provided as either of 2 unique byte arrays. Lotus block validation functions perform a uniqueness check on provided blocks. Two blocks are considered distinct if the CIDs of their blockheader do not match. The CID method for blockheader includes the BlockSig of the block. The result of these issues is that it would be possible to punish miners for valid blocks, as there are two different valid block CIDs available for each block, even though this must be unique. By switching from the go based `blst` bindings over to the bindings in `filecoin-ffi`, the code paths now ensure that all signatures are compressed by size and the way they are deserialized. This happened in https://github.com/filecoin-project/lotus/pull/5393."
          }
        ]
      },
      "impact": {
        "cvss": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.9,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N",
          "version": "3.1"
        }
      },
      "problemtype": {
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          {
            "description": [
              {
                "lang": "eng",
                "value": "CWE-347 Improper Verification of Cryptographic Signature"
              }
            ]
          }
        ]
      },
      "references": {
        "reference_data": [
          {
            "name": "https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvh",
            "refsource": "CONFIRM",
            "url": "https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvh"
          },
          {
            "name": "https://github.com/filecoin-project/lotus/pull/5393",
            "refsource": "MISC",
            "url": "https://github.com/filecoin-project/lotus/pull/5393"
          },
          {
            "name": "https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754",
            "refsource": "MISC",
            "url": "https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754"
          }
        ]
      },
      "source": {
        "advisory": "GHSA-4g52-pqcj-phvh",
        "discovery": "UNKNOWN"
      }
    },
    "gitlab.com": {
      "advisories": [
        {
          "affected_range": "\u003c1.5.0",
          "affected_versions": "All versions before 1.5.0",
          "cvss_v2": "AV:N/AC:L/Au:N/C:N/I:P/A:N",
          "cvss_v3": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
          "cwe_ids": [
            "CWE-1035",
            "CWE-347",
            "CWE-937"
          ],
          "date": "2021-05-21",
          "description": "Lotus is an Implementation of the Filecoin protocol written in Go. BLS signature validation in lotus uses blst library method VerifyCompressed. This method accepts signatures in 2 forms: \"serialized\", and \"compressed\", meaning that BLS signatures can be provided as either of 2 unique byte arrays. Lotus block validation functions perform a uniqueness check on provided blocks. Two blocks are considered distinct if the CIDs of their blockheader do not match. The CID method for blockheader includes the BlockSig of the block. The result of these issues is that it would be possible to punish miners for valid blocks, as there are two different valid block CIDs available for each block, even though this must be unique. By switching from the go based `blst` bindings over to the bindings in `filecoin-ffi`, the code paths now ensure that all signatures are compressed by size and the way they are deserialized. This happened in https://github.com/filecoin-project/lotus/pull/5393.",
          "fixed_versions": [
            "1.5.0"
          ],
          "identifier": "CVE-2021-21405",
          "identifiers": [
            "GHSA-4g52-pqcj-phvh",
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          ],
          "not_impacted": "All versions starting from 1.5.0",
          "package_slug": "go/github.com/filecoin-project/lotus",
          "pubdate": "2021-05-21",
          "solution": "Upgrade to version 1.5.0 or above.",
          "title": "Improper Verification of Cryptographic Signature",
          "urls": [
            "https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvh",
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            "https://github.com/filecoin-project/lotus/pull/5393",
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            "https://github.com/advisories/GHSA-4g52-pqcj-phvh"
          ],
          "uuid": "d0c00b26-637d-495a-adea-5d3146c8cc20"
        }
      ]
    },
    "nvd.nist.gov": {
      "configurations": {
        "CVE_data_version": "4.0",
        "nodes": [
          {
            "children": [],
            "cpe_match": [
              {
                "cpe23Uri": "cpe:2.3:a:filecoin:lotus:*:*:*:*:*:*:*:*",
                "cpe_name": [],
                "versionEndExcluding": "1.5.0",
                "vulnerable": true
              }
            ],
            "operator": "OR"
          }
        ]
      },
      "cve": {
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          "ASSIGNER": "security-advisories@github.com",
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        "description": {
          "description_data": [
            {
              "lang": "en",
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            }
          ]
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        "problemtype": {
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        }
      },
      "lastModifiedDate": "2021-04-23T14:40Z",
      "publishedDate": "2021-04-15T22:15Z"
    }
  }
}

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

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How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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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.

Action not permitted

CVE-2021-21405 (GCVE-0-2021-21405)

FKIE_CVE-2021-21405

GHSA-4G52-PQCJ-PHVH

Impact

Patches

References

GSD-2021-21405

Tags

Sightings

Nomenclature

Vulnerability timeline

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