GCVE Workshop - 22 September 2026 (14:00-18:00), Luxembourg Before The Vulnopticon Conference - Registration

CVE-2023-32323 (GCVE-0-2023-32323)

Vulnerability from cvelistv5 – Published: 2023-05-26 13:32 – Updated: 2025-02-13 16:50
VLAI
Title
Synapse Outgoing federation to specific hosts can be disabled by sending malicious invites
Summary
Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. A malicious user on a Synapse homeserver X with permission to create certain state events can disable outbound federation from X to an arbitrary homeserver Y. Synapse instances with federation disabled are not affected. In versions of Synapse up to and including 1.73, Synapse did not limit the size of `invite_room_state`, meaning that it was possible to create an arbitrarily large invite event. Synapse 1.74 refuses to create oversized `invite_room_state` fields. Server operators should upgrade to Synapse 1.74 or newer urgently.
Severity
5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-01-14 20:00 UTC
CWE
  • CWE-20 - Improper Input Validation
Assigner
References
Impacted products
Vendor Product Version CPE status
matrix-org synapse Affected: < 1.74.0
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-02T15:10:24.899Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "name": "https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr",
            "tags": [
              "x_refsource_CONFIRM",
              "x_transferred"
            ],
            "url": "https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr"
          },
          {
            "name": "https://github.com/matrix-org/synapse/issues/14492",
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/matrix-org/synapse/issues/14492"
          },
          {
            "name": "https://github.com/matrix-org/synapse/pull/14642",
            "tags": [
              "x_refsource_MISC",
              "x_transferred"
            ],
            "url": "https://github.com/matrix-org/synapse/pull/14642"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/"
          }
        ],
        "title": "CVE Program Container"
      },
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2023-32323",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-01-14T20:00:17.125564Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-01-14T20:00:25.608Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "synapse",
          "vendor": "matrix-org",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.74.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. A malicious user on a Synapse homeserver X with permission to create certain state events can disable outbound federation from X to an arbitrary homeserver Y. Synapse instances with federation disabled are not affected. In versions of Synapse up to and including 1.73, Synapse did not limit the size of `invite_room_state`, meaning that it was possible to create an arbitrarily large invite event. Synapse 1.74 refuses to create oversized `invite_room_state` fields. Server operators should upgrade to Synapse 1.74 or newer urgently."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-20",
              "description": "CWE-20: Improper Input Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2023-09-18T03:06:07.780Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr"
        },
        {
          "name": "https://github.com/matrix-org/synapse/issues/14492",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/matrix-org/synapse/issues/14492"
        },
        {
          "name": "https://github.com/matrix-org/synapse/pull/14642",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/matrix-org/synapse/pull/14642"
        },
        {
          "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/"
        }
      ],
      "source": {
        "advisory": "GHSA-f3wc-3vxv-xmvr",
        "discovery": "UNKNOWN"
      },
      "title": "Synapse Outgoing federation to specific hosts can be disabled by sending malicious invites"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2023-32323",
    "datePublished": "2023-05-26T13:32:01.632Z",
    "dateReserved": "2023-05-08T13:26:03.880Z",
    "dateUpdated": "2025-02-13T16:50:32.310Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2023-32323",
      "date": "2026-09-19",
      "epss": "0.00981",
      "percentile": "0.60746"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "synapse",
                "vendor": "matrix-org",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003c 1.74.0"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "D7B262AE-3361-41B7-8BF8-D893316A98C4",
                    "versionEndExcluding": "1.74.0",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. A malicious user on a Synapse homeserver X with permission to create certain state events can disable outbound federation from X to an arbitrary homeserver Y. Synapse instances with federation disabled are not affected. In versions of Synapse up to and including 1.73, Synapse did not limit the size of `invite_room_state`, meaning that it was possible to create an arbitrarily large invite event. Synapse 1.74 refuses to create oversized `invite_room_state` fields. Server operators should upgrade to Synapse 1.74 or newer urgently."
          },
          {
            "lang": "es",
            "value": "Synapse es un servidor dom\u00e9stico Matrix de c\u00f3digo abierto escrito y mantenido por la Fundaci\u00f3n Matrix.org. Un usuario malicioso en un servidor dom\u00e9stico X de Synapse con permiso para crear ciertos eventos de estado puede deshabilitar la federaci\u00f3n saliente de X a un servidor dom\u00e9stico Y arbitrario. Las instancias de Synapse con la federaci\u00f3n deshabilitada no se ven afectadas. En las versiones de Synapse hasta la 1.73 inclusive, Synapse no limitaba el tama\u00f1o de `invite_room_state`, lo que significa que era posible crear un evento de invitaci\u00f3n arbitrariamente grande. Synapse 1.74 se niega a crear campos `invite_room_state` de gran tama\u00f1o. Los operadores de servidores deben actualizar urgentemente a Synapse 1.74 o posterior."
          }
        ],
        "id": "CVE-2023-32323",
        "lastModified": "2026-06-17T05:58:34.297",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "LOW",
                "baseScore": 5.0,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "CHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L",
                "version": "3.1"
              },
              "exploitabilityScore": 3.1,
              "impactScore": 1.4,
              "source": "security-advisories@github.com",
              "type": "Secondary"
            },
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "LOW",
                "baseScore": 4.3,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
                "version": "3.1"
              },
              "exploitabilityScore": 2.8,
              "impactScore": 1.4,
              "source": "nvd@nist.gov",
              "type": "Primary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2023-32323",
                "options": [
                  {
                    "exploitation": "poc"
                  },
                  {
                    "automatable": "no"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-01-14T20:00:17.125564Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2023-05-26T14:15:10.827",
        "references": [
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Exploit",
              "Issue Tracking"
            ],
            "url": "https://github.com/matrix-org/synapse/issues/14492"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Patch"
            ],
            "url": "https://github.com/matrix-org/synapse/pull/14642"
          },
          {
            "source": "security-advisories@github.com",
            "tags": [
              "Mitigation",
              "Vendor Advisory"
            ],
            "url": "https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Exploit",
              "Issue Tracking"
            ],
            "url": "https://github.com/matrix-org/synapse/issues/14492"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Patch"
            ],
            "url": "https://github.com/matrix-org/synapse/pull/14642"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "tags": [
              "Mitigation",
              "Vendor Advisory"
            ],
            "url": "https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr"
          },
          {
            "source": "af854a3a-2127-422b-91ae-364da2661108",
            "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Modified",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-20"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Secondary"
          },
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-20"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "current_release_date": "2025-11-21T15:35:45+00:00",
      "cve": "CVE-2023-32323",
      "id": "CVE-2023-32323",
      "initial_release_date": "2023-05-25T00:00:00+00:00",
      "product_status:known_not_affected": "1",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "matrix-synapse: Synapse Outgoing federation to specific hosts can be disabled by sending malicious invites",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-32323.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "providerMetadata": {
              "dateUpdated": "2024-08-02T15:10:24.899Z",
              "orgId": "af854a3a-2127-422b-91ae-364da2661108",
              "shortName": "CVE"
            },
            "references": [
              {
                "name": "https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr",
                "tags": [
                  "x_refsource_CONFIRM",
                  "x_transferred"
                ],
                "url": "https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr"
              },
              {
                "name": "https://github.com/matrix-org/synapse/issues/14492",
                "tags": [
                  "x_refsource_MISC",
                  "x_transferred"
                ],
                "url": "https://github.com/matrix-org/synapse/issues/14492"
              },
              {
                "name": "https://github.com/matrix-org/synapse/pull/14642",
                "tags": [
                  "x_refsource_MISC",
                  "x_transferred"
                ],
                "url": "https://github.com/matrix-org/synapse/pull/14642"
              },
              {
                "tags": [
                  "x_transferred"
                ],
                "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/"
              }
            ],
            "title": "CVE Program Container"
          },
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2023-32323",
                    "options": [
                      {
                        "Exploitation": "poc"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2025-01-14T20:00:17.125564Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2025-01-14T20:00:21.614Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "product": "synapse",
              "vendor": "matrix-org",
              "versions": [
                {
                  "status": "affected",
                  "version": "\u003c 1.74.0"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. A malicious user on a Synapse homeserver X with permission to create certain state events can disable outbound federation from X to an arbitrary homeserver Y. Synapse instances with federation disabled are not affected. In versions of Synapse up to and including 1.73, Synapse did not limit the size of `invite_room_state`, meaning that it was possible to create an arbitrarily large invite event. Synapse 1.74 refuses to create oversized `invite_room_state` fields. Server operators should upgrade to Synapse 1.74 or newer urgently."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "LOW",
                "baseScore": 5,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "CHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L",
                "version": "3.1"
              }
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-20",
                  "description": "CWE-20: Improper Input Validation",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2023-09-18T03:06:07.780Z",
            "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
            "shortName": "GitHub_M"
          },
          "references": [
            {
              "name": "https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr",
              "tags": [
                "x_refsource_CONFIRM"
              ],
              "url": "https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvr"
            },
            {
              "name": "https://github.com/matrix-org/synapse/issues/14492",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/matrix-org/synapse/issues/14492"
            },
            {
              "name": "https://github.com/matrix-org/synapse/pull/14642",
              "tags": [
                "x_refsource_MISC"
              ],
              "url": "https://github.com/matrix-org/synapse/pull/14642"
            },
            {
              "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/"
            }
          ],
          "source": {
            "advisory": "GHSA-f3wc-3vxv-xmvr",
            "discovery": "UNKNOWN"
          },
          "title": "Synapse Outgoing federation to specific hosts can be disabled by sending malicious invites"
        }
      },
      "cveMetadata": {
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "assignerShortName": "GitHub_M",
        "cveId": "CVE-2023-32323",
        "datePublished": "2023-05-26T13:32:01.632Z",
        "dateReserved": "2023-05-08T13:26:03.880Z",
        "dateUpdated": "2025-02-13T16:50:32.310Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.1"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.


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.