FKIE_CVE-2026-45122

Vulnerability from fkie_nvd - Published: 2026-08-18 16:17 - Updated: 2026-08-18 18:17
Severity
4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Summary
MyBB is free and open source forum software. Prior to 1.8.40, the calendar module does not validate moderation permissions for the destination calendar when moving events. A user with moderation permission for the source calendar can move an event to a calendar where the user has only viewing permission because the do_move action in calendar.php does not check canmoderateevents for the target calendar. The uniquely identifying implementation details include calendar event move, source calendar moderation permission, and destination calendar viewing permission. This issue is fixed in version 1.8.40.
References
security-advisories@github.comhttps://github.com/mybb/mybb/commit/86ed2058e7f9a2c14828e731f684e997f9bb220c
security-advisories@github.comhttps://github.com/mybb/mybb/releases/tag/mybb_1840
security-advisories@github.comhttps://github.com/mybb/mybb/security/advisories/GHSA-839m-gpw8-59j4
security-advisories@github.comhttps://mybb.com/versions/1.8.40
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "mybb",
          "vendor": "mybb",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.8.40"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "MyBB is free and open source forum software. Prior to 1.8.40, the calendar module does not validate moderation permissions for the destination calendar when moving events. A user with moderation permission for the source calendar can move an event to a calendar where the user has only viewing permission because the do_move action in calendar.php does not check canmoderateevents for the target calendar. The uniquely identifying implementation details include calendar event move, source calendar moderation permission, and destination calendar viewing permission. This issue is fixed in version 1.8.40."
    }
  ],
  "id": "CVE-2026-45122",
  "lastModified": "2026-08-18T18:17:35.967",
  "metrics": {
    "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": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-45122",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-18T17:52:37.864441Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-18T16:17:07.243",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mybb/mybb/commit/86ed2058e7f9a2c14828e731f684e997f9bb220c"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mybb/mybb/releases/tag/mybb_1840"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mybb/mybb/security/advisories/GHSA-839m-gpw8-59j4"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://mybb.com/versions/1.8.40"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-863"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}



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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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