Security advisory

{
  "id": "121bff8943aa8e8a085835b53984b0dc4002da4490a4996c6ae77128e80202d1",
  "url": "https://osv.dev/vulnerability/CVE-2021-32659",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-32659",
    "summary": "Matrix-appservice-bridge is the bridging service for the Matrix communication program's application services. In versions 2.6.0 and earlier, if a bridge has room upgrade handling turned on in the configuration (the `roomUpgradeOpts` key when instantiating a new `Bridge` instance.), any `m.room.tombstone` event it encounters will be used to unbridge the current room and bridge into the target room. However, the target room `m.room.create` event is not checked to verify if the `predecessor` field contains the previous room. This means that any malicious admin of a bridged room can repoint the traffic to a different room without the new room being aware. Versions 2.6.1 and greater are patched. As a workaround, disabling the automatic room upgrade handling can be done by removing the `roomUpgradeOpts` key from the `Bridge` class options.",
    "evidence": "osv:CVE-2021-32659",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-32659",
      "aliases": [
        "CVE-2021-32659",
        "GHSA-35g4-qx3c-vjhx"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/matrix-org/matrix-appservice-bridge",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "7e32516a211b9d13433fc5a6016642e3ad2fc974"
                },
                {
                  "fixed": "b69e745584a34fcfd858df33e4631e420da07b9f"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:matrix:matrix-appservice-bridge:*:*:*:*:*:node.js:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.6.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "b69e745584a34fcfd858df33e4631e420da07b9f"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "7e32516a211b9d13433fc5a6016642e3ad2fc974"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "2.6.1"
                  }
                ]
              }
            }
          ],
          "versions": [
            "2.6.0",
            "2.6.0-rc1",
            "2.5.0",
            "v2.5.0-rc1",
            "2.4.0",
            "2.4.0-rc2",
            "2.4.0-rc1",
            "2.3.1",
            "2.3.0",
            "2.3.0-rc3",
            "2.3.0-rc2",
            "2.3.0-rc1",
            "2.2.0",
            "2.2.0-rc2",
            "2.2.0-rc1",
            "2.1.0",
            "2.1.0-rc2",
            "2.1.0-rc1",
            "2.0.0",
            "v1.13.2",
            "1.13.1",
            "1.13.0",
            "1.12.2",
            "1.12.1",
            "1.12.0",
            "1.11.1",
            "1.11.0",
            "1.10.2",
            "1.10.0",
            "1.7.0",
            "1.6.0c",
            "1.6.0b",
            "1.6.0a",
            "1.6.0",
            "1.4.0a",
            "1.4.0",
            "1.3.0",
            "1.2.1",
            "1.1.1",
            "1.0.1",
            "1.0.0",
            "0.3.6",
            "0.3.5",
            "0.3.4",
            "0.3.3",
            "0.3.2",
            "0.1.5",
            "0.1.4",
            "0.1.3",
            "0.1.2",
            "0.1.1",
            "0.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-32659.json"
          }
        }
      ],
      "modified": "2026-10-20T10:54:43.349026922Z",
      "provider": "osv",
      "references": [
        "https://github.com/matrix-org/matrix-appservice-bridge/security/advisories/GHSA-35g4-qx3c-vjhx",
        "https://github.com/matrix-org/matrix-appservice-bridge/commit/b69e745584a34fcfd858df33e4631e420da07b9f",
        "https://github.com/matrix-org/matrix-appservice-bridge/releases/tag/2.6.1"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-32659",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 385997,
  "published_at": "2021-06-16T19:15:38.83+00:00"
}