ghsa-2hwx-mjrm-v3g8
Vulnerability from github
Published
2021-03-01 19:34
Modified
2024-09-30 20:23
Severity ?
4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
5.3 (Medium) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Summary
Denial of service attack via .well-known lookups
Details

Impact

A malicious homeserver could redirect requests to their .well-known file to a large file. This can lead to a denial of service attack where homeservers will consume significantly more resources when requesting the .well-known file of a malicious homeserver.

This affects any server which accepts federation requests from untrusted servers.

Patches

Issue is resolved by #8950. A bug not affecting the security aspects of this was fixed in #9108.

Workarounds

The federation_domain_whitelist setting can be used to restrict the homeservers communicated with over federation.

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "matrix-synapse"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.99.0"
            },
            {
              "fixed": "1.25.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2021-21274"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2021-03-01T19:03:06Z",
    "nvd_published_at": "2021-02-26T18:15:00Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\nA malicious homeserver could redirect requests to their .well-known file to a large file. This can lead to a denial of service attack where homeservers will consume significantly more resources when requesting the .well-known file of a malicious homeserver.\n\nThis affects any server which accepts federation requests from untrusted servers.\n\n### Patches\nIssue is resolved by #8950. A bug not affecting the security aspects of this was fixed in #9108.\n\n### Workarounds\nThe `federation_domain_whitelist` setting can be used to restrict the homeservers communicated with over federation.",
  "id": "GHSA-2hwx-mjrm-v3g8",
  "modified": "2024-09-30T20:23:54Z",
  "published": "2021-03-01T19:34:54Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/matrix-org/synapse/security/advisories/GHSA-2hwx-mjrm-v3g8"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21274"
    },
    {
      "type": "WEB",
      "url": "https://github.com/matrix-org/synapse/pull/8950"
    },
    {
      "type": "WEB",
      "url": "https://github.com/matrix-org/synapse/commit/ff5c4da1289cb5e097902b3e55b771be342c29d6"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/matrix-org/synapse"
    },
    {
      "type": "WEB",
      "url": "https://github.com/matrix-org/synapse/releases/tag/v1.25.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2021-132.yaml"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Denial of service attack via .well-known lookups"
}


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