FKIE_CVE-2021-30477

Vulnerability from fkie_nvd - Published: 2021-04-15 00:15 - Updated: 2026-06-17 03:50
Severity
4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Summary
An issue was discovered in Zulip Server before 3.4. A bug in the implementation of replies to messages sent by outgoing webhooks to private streams meant that an outgoing webhook bot could be used to send messages to private streams that the user was not intended to be able to send messages to.
References
cve@mitre.orghttps://blog.zulip.com/2021/04/14/zulip-server-3-4/Release Notes, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://blog.zulip.com/2021/04/14/zulip-server-3-4/Release Notes, Vendor Advisory
Impacted products
Vendor Product Version
zulip zulip_server *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "n/a",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ],
      "source": "cve@mitre.org"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:zulip:zulip_server:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "09622761-7CB9-4FD7-82B0-B80CD94D296D",
              "versionEndExcluding": "3.4",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "An issue was discovered in Zulip Server before 3.4. A bug in the implementation of replies to messages sent by outgoing webhooks to private streams meant that an outgoing webhook bot could be used to send messages to private streams that the user was not intended to be able to send messages to."
    },
    {
      "lang": "es",
      "value": "Se detect\u00f3 un problema en Zulip Server versiones anteriores a 3.4.\u0026#xa0;Un bug en la implementaci\u00f3n de las respuestas a los mensajes enviados por webhooks salientes a transmisiones privadas significaba que un bot webhook saliente pod\u00eda usarse para enviar mensajes a transmisiones privadas a las que el usuario no ten\u00eda la intenci\u00f3n de poder enviar mensajes"
    }
  ],
  "id": "CVE-2021-30477",
  "lastModified": "2026-06-17T03:50:18.860",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "MEDIUM",
        "cvssData": {
          "accessComplexity": "LOW",
          "accessVector": "NETWORK",
          "authentication": "SINGLE",
          "availabilityImpact": "NONE",
          "baseScore": 4.0,
          "confidentialityImpact": "NONE",
          "integrityImpact": "PARTIAL",
          "vectorString": "AV:N/AC:L/Au:S/C:N/I:P/A:N",
          "version": "2.0"
        },
        "exploitabilityScore": 8.0,
        "impactScore": 2.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "nvd@nist.gov",
        "type": "Primary",
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 1.4,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2021-04-15T00:15:13.047",
  "references": [
    {
      "source": "cve@mitre.org",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "url": "https://blog.zulip.com/2021/04/14/zulip-server-3-4/"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "url": "https://blog.zulip.com/2021/04/14/zulip-server-3-4/"
    }
  ],
  "sourceIdentifier": "cve@mitre.org",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}



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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.