FKIE_CVE-2025-66511

Vulnerability from fkie_nvd - Published: 2025-12-05 17:16 - Updated: 2025-12-10 16:14
Severity ?
4.8 (Medium) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Summary
Nextcloud Calendar is a calendar app for Nextcloud. Prior to 6.0.3, the Calendar app generates participant tokens for meeting proposals using a hash function, allowing an attacker to compute valid participant tokens, which allowed them to request details and submit dates in meeting proposals. The tokens are not purely random generated. This vulnerability is fixed in 6.0.3.
References
security-advisories@github.comhttps://github.com/nextcloud/calendar/commit/8de14ae87f321f5f09280d9895a27d54d24f33fbPatch
security-advisories@github.comhttps://github.com/nextcloud/calendar/pull/7659Issue Tracking
security-advisories@github.comhttps://github.com/nextcloud/security-advisories/security/advisories/GHSA-whm3-vv55-gf27Patch, Vendor Advisory
security-advisories@github.comhttps://hackerone.com/reports/3385434Permissions Required, Vendor Advisory
Impacted products
Vendor Product Version
nextcloud calendar *
To clipboard 

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    {
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              "criteria": "cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "24F60C27-884F-4BF3-A50E-D189CA2DBC02",
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      "value": "Nextcloud Calendar is a calendar app for Nextcloud. Prior to 6.0.3, the Calendar app generates participant tokens for meeting proposals using a hash function, allowing an attacker to compute valid participant tokens, which allowed them to request details and submit dates in meeting proposals. The tokens are not purely random generated. This vulnerability is fixed in 6.0.3."
    }
  ],
  "id": "CVE-2025-66511",
  "lastModified": "2025-12-10T16:14:27.230",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 4.8,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
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          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
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  "vulnStatus": "Analyzed",
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          "value": "CWE-330"
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}


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  • 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.
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  • 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.



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