Vulnerability-Lookup

Vulnerability from bitnami_vulndb

Published

2024-07-24 19:38

Modified

2026-09-08 08:34

Summary

Crash due to malformed relay protocol message

Details

Syncthing is a continuous file synchronization program. In Syncthing before version 1.15.0, the relay server strelaysrv can be caused to crash and exit by sending a relay message with a negative length field. Similarly, Syncthing itself can crash for the same reason if given a malformed message from a malicious relay server when attempting to join the relay. Relay joins are essentially random (from a subset of low latency relays) and Syncthing will by default restart when crashing, at which point it's likely to pick another non-malicious relay. This flaw is fixed in version 1.15.0.

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Bitnami",
        "name": "syncthing",
        "purl": "pkg:bitnami/syncthing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.15.0"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "severity": [
        {
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "type": "CVSS_V3"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-21404"
  ],
  "database_specific": {
    "cpes": [
      "cpe:2.3:a:syncthing:syncthing:*:*:*:*:*:*:*:*"
    ],
    "severity": "High"
  },
  "details": "Syncthing is a continuous file synchronization program. In Syncthing before version 1.15.0, the relay server `strelaysrv` can be caused to crash and exit by sending a relay message with a negative length field. Similarly, Syncthing itself can crash for the same reason if given a malformed message from a malicious relay server when attempting to join the relay. Relay joins are essentially random (from a subset of low latency relays) and Syncthing will by default restart when crashing, at which point it\u0027s likely to pick another non-malicious relay. This flaw is fixed in version 1.15.0.",
  "id": "BIT-syncthing-2021-21404",
  "modified": "2026-09-08T08:34:36.952Z",
  "published": "2024-07-24T19:38:44.658Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/syncthing/syncthing/commit/fb4fdaf4c0a79c22cad000c42ac1394e3ccb6a97"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/syncthing/syncthing/releases/tag/v1.15.0"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/syncthing/syncthing/security/advisories/GHSA-x462-89pf-6r5h"
    },
    {
      "type": "ADVISORY",
      "url": "https://pkg.go.dev/github.com/syncthing/syncthing"
    },
    {
      "type": "WEB",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21404"
    }
  ],
  "schema_version": "1.5.0",
  "summary": "Crash due to malformed relay protocol message"
}

CVE-2021-21404 (GCVE-0-2021-21404)

Vulnerability from cvelistv5 – Published: 2021-04-06 20:00 – Updated: 2024-08-03 18:09

Title

Crash due to malformed relay protocol message

Summary

Syncthing is a continuous file synchronization program. In Syncthing before version 1.15.0, the relay server `strelaysrv` can be caused to crash and exit by sending a relay message with a negative length field. Similarly, Syncthing itself can crash for the same reason if given a malformed message from a malicious relay server when attempting to join the relay. Relay joins are essentially random (from a subset of low latency relays) and Syncthing will by default restart when crashing, at which point it's likely to pick another non-malicious relay. This flaw is fixed in version 1.15.0.

Severity

7.5 (High)


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

CWE

CWE-20 - Improper Input Validation

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7771 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/syncthing/syncthing/security/a…	x_refsource_CONFIRM
https://pkg.go.dev/github.com/syncthing/syncthing	x_refsource_MISC
https://github.com/syncthing/syncthing/commit/fb4…	x_refsource_MISC
https://github.com/syncthing/syncthing/releases/t…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
syncthing	syncthing	Affected: < 1.15.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
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        "providerMetadata": {
          "dateUpdated": "2024-08-03T18:09:16.158Z",
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        "references": [
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            ],
            "url": "https://github.com/syncthing/syncthing/security/advisories/GHSA-x462-89pf-6r5h"
          },
          {
            "tags": [
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            ],
            "url": "https://pkg.go.dev/github.com/syncthing/syncthing"
          },
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            "tags": [
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            ],
            "url": "https://github.com/syncthing/syncthing/commit/fb4fdaf4c0a79c22cad000c42ac1394e3ccb6a97"
          },
          {
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/syncthing/syncthing/releases/tag/v1.15.0"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "syncthing",
          "vendor": "syncthing",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.15.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Syncthing is a continuous file synchronization program. In Syncthing before version 1.15.0, the relay server `strelaysrv` can be caused to crash and exit by sending a relay message with a negative length field. Similarly, Syncthing itself can crash for the same reason if given a malformed message from a malicious relay server when attempting to join the relay. Relay joins are essentially random (from a subset of low latency relays) and Syncthing will by default restart when crashing, at which point it\u0027s likely to pick another non-malicious relay. This flaw is fixed in version 1.15.0."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
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          }
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            }
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      "providerMetadata": {
        "dateUpdated": "2021-04-06T20:00:15.000Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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      },
      "references": [
        {
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          ],
          "url": "https://github.com/syncthing/syncthing/security/advisories/GHSA-x462-89pf-6r5h"
        },
        {
          "tags": [
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          "url": "https://pkg.go.dev/github.com/syncthing/syncthing"
        },
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            "x_refsource_MISC"
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          "url": "https://github.com/syncthing/syncthing/commit/fb4fdaf4c0a79c22cad000c42ac1394e3ccb6a97"
        },
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          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/syncthing/syncthing/releases/tag/v1.15.0"
        }
      ],
      "source": {
        "advisory": "GHSA-x462-89pf-6r5h",
        "discovery": "UNKNOWN"
      },
      "title": "Crash due to malformed relay protocol message",
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        },
        "affects": {
          "vendor": {
            "vendor_data": [
              {
                "product": {
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                    {
                      "product_name": "syncthing",
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                          {
                            "version_value": "\u003c 1.15.0"
                          }
                        ]
                      }
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  },
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}

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

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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.

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