CVE-2026-100404 (GCVE-0-2026-100404)

Vulnerability from cvelistv5 – Published: 2026-10-14 15:50 – Updated: 2026-10-14 15:50
VLAI
Title
Zulip: Guests can read new messages in non-subscribed public channels
Summary
Zulip is an open-source team collaboration tool. In Zulip Server versions through 12.1, guest users can receive new message events for public channels outside their subscriptions. A guest can trigger the issue by registering an event queue with parameters that request messages from an unsubscribed public channel, or an existing event queue can remain affected after the guest's access to the channel is removed. The flaw discloses new public-channel messages to the guest. This issue is fixed in version 12.2.
Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CWE
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7637 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
zulip zulip Affected: < 12.2
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "zulip",
          "vendor": "zulip",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 12.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Zulip is an open-source team collaboration tool. In Zulip Server versions through 12.1, guest users can receive new message events for public channels outside their subscriptions. A guest can trigger the issue by registering an event queue with parameters that request messages from an unsubscribed public channel, or an existing event queue can remain affected after the guest\u0027s access to the channel is removed. The flaw discloses new public-channel messages to the guest. This issue is fixed in version 12.2."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-862",
              "description": "CWE-862: Missing Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-14T15:50:00.354Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/zulip/zulip/security/advisories/GHSA-5r8f-gq2h-fcgp",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/zulip/zulip/security/advisories/GHSA-5r8f-gq2h-fcgp"
        },
        {
          "name": "https://github.com/zulip/zulip/pull/39913",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/zulip/zulip/pull/39913"
        },
        {
          "name": "https://github.com/zulip/zulip/commit/98659a41cb93d4ce329ea14bb0cdfb4b147500ba",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/zulip/zulip/commit/98659a41cb93d4ce329ea14bb0cdfb4b147500ba"
        },
        {
          "name": "https://github.com/zulip/zulip/commit/c03db8916456674df3c98614f6f0ef8cd024ef11",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/zulip/zulip/commit/c03db8916456674df3c98614f6f0ef8cd024ef11"
        },
        {
          "name": "https://github.com/zulip/zulip/releases/tag/12.2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/zulip/zulip/releases/tag/12.2"
        }
      ],
      "source": {
        "advisory": "GHSA-5r8f-gq2h-fcgp",
        "discovery": "UNKNOWN"
      },
      "title": "Zulip: Guests can read new messages in non-subscribed public channels"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-100404",
    "datePublished": "2026-10-14T15:50:00.354Z",
    "dateReserved": "2026-09-25T20:08:33.083Z",
    "dateUpdated": "2026-10-14T15:50:00.354Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "zulip",
                "vendor": "zulip",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003c 12.2"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Zulip is an open-source team collaboration tool. In Zulip Server versions through 12.1, guest users can receive new message events for public channels outside their subscriptions. A guest can trigger the issue by registering an event queue with parameters that request messages from an unsubscribed public channel, or an existing event queue can remain affected after the guest\u0027s access to the channel is removed. The flaw discloses new public-channel messages to the guest. This issue is fixed in version 12.2."
          }
        ],
        "id": "CVE-2026-100404",
        "lastModified": "2026-10-14T16:17:28.860",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "NONE",
                "baseScore": 6.5,
                "baseSeverity": "MEDIUM",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
                "version": "3.1"
              },
              "exploitabilityScore": 2.8,
              "impactScore": 3.6,
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-10-14T16:17:28.860",
        "references": [
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/zulip/zulip/commit/98659a41cb93d4ce329ea14bb0cdfb4b147500ba"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/zulip/zulip/commit/c03db8916456674df3c98614f6f0ef8cd024ef11"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/zulip/zulip/pull/39913"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/zulip/zulip/releases/tag/12.2"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/zulip/zulip/security/advisories/GHSA-5r8f-gq2h-fcgp"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Received",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-862"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Primary"
          }
        ]
      }
    }
  }
}



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