FKIE_CVE-2026-45286

Vulnerability from fkie_nvd - Published: 2026-06-01 19:16 - Updated: 2026-06-03 20:35
Severity
4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Summary
Nextcloud is an open source content collaboration platform. From versions 5.5.13 to before 5.5.17, and 6.2.0 to before 6.2.3, an authenticated user can enumerate users on the same Nextcloud instance by using the Calendar app's endpoint for suggesting attendees. The sharing restrictions, applied to other endpoints, were not effective here. This issue has been patched in versions 5.5.17 and 6.2.3.
References
security-advisories@github.comhttps://github.com/nextcloud/calendar/issues/7971Exploit, Issue Tracking, Patch
security-advisories@github.comhttps://github.com/nextcloud/calendar/pull/8197Issue Tracking, Patch
security-advisories@github.comhttps://github.com/nextcloud/security-advisories/security/advisories/GHSA-r697-74m9-gvf2Mitigation, Vendor Advisory
security-advisories@github.comhttps://hackerone.com/reports/3540663Permissions Required
Impacted products
Vendor Product Version
nextcloud calendar *
nextcloud calendar *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "1CF598EB-40C6-4DD2-91AB-C6F9E1B3E822",
              "versionEndExcluding": "5.5.17",
              "versionStartIncluding": "5.5.13",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "ED61C839-05B9-4A73-B437-9EA6010FB468",
              "versionEndExcluding": "6.2.3",
              "versionStartIncluding": "6.2.0",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Nextcloud is an open source content collaboration platform. From versions 5.5.13 to before 5.5.17, and 6.2.0 to before 6.2.3, an authenticated user can enumerate users on the same Nextcloud instance by using the Calendar app\u0027s endpoint for suggesting attendees. The sharing restrictions, applied to other endpoints, were not effective here. This issue has been patched in versions 5.5.17 and 6.2.3."
    }
  ],
  "id": "CVE-2026-45286",
  "lastModified": "2026-06-03T20:35:59.817",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 1.4,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-06-01T19:16:50.957",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Issue Tracking",
        "Patch"
      ],
      "url": "https://github.com/nextcloud/calendar/issues/7971"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Issue Tracking",
        "Patch"
      ],
      "url": "https://github.com/nextcloud/calendar/pull/8197"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/nextcloud/security-advisories/security/advisories/GHSA-r697-74m9-gvf2"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Permissions Required"
      ],
      "url": "https://hackerone.com/reports/3540663"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-200"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    },
    {
      "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.