FKIE_CVE-2026-28736

Vulnerability from fkie_nvd - Published: 2026-04-03 14:16 - Updated: 2026-07-24 21:10
Severity
4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Summary
** UNSUPPORTED WHEN ASSIGNED ** Focalboard version 8.0 fails to validate file ownership when serving uploaded files. This allows an authenticated attacker who knows a victim's fileID to read the content of the file. NOTE: Focalboard as a standalone product is not maintained and no fix will be issued.
References
responsibledisclosure@mattermost.comhttps://github.com/mattermost-community/focalboardProduct
Impacted products
Vendor Product Version
mattermost focalboard 8.0.0
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Focalboard",
          "vendor": "Mattermost",
          "versions": [
            {
              "lessThanOrEqual": "8.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "responsibledisclosure@mattermost.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:mattermost:focalboard:8.0.0:*:*:*:*:*:*:*",
              "matchCriteriaId": "42087E46-C9CC-46D7-B424-55537457FE0A",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [
    {
      "sourceIdentifier": "responsibledisclosure@mattermost.com",
      "tags": [
        "unsupported-when-assigned"
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "** UNSUPPORTED WHEN ASSIGNED ** Focalboard version 8.0 fails to validate file ownership when serving uploaded files. This allows an authenticated attacker who knows a victim\u0027s fileID to read the content of the file. NOTE: Focalboard as a standalone product is not maintained and no fix will be issued."
    },
    {
      "lang": "es",
      "value": " NO COMPATIBLE CUANDO ASIGNADO  La versi\u00f3n 8.0 de Focalboard no valida la propiedad de los archivos al servir archivos subidos. Esto permite a un atacante autenticado que conoce el ID de archivo de una v\u00edctima leer el contenido del archivo. NOTA: Focalboard como producto independiente no recibe mantenimiento y no se emitir\u00e1 ninguna correcci\u00f3n."
    }
  ],
  "id": "CVE-2026-28736",
  "lastModified": "2026-07-24T21:10:00.143",
  "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": "responsibledisclosure@mattermost.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-28736",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-04-03T14:53:54.422014Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-04-03T14:16:29.517",
  "references": [
    {
      "source": "responsibledisclosure@mattermost.com",
      "tags": [
        "Product"
      ],
      "url": "https://github.com/mattermost-community/focalboard"
    }
  ],
  "sourceIdentifier": "responsibledisclosure@mattermost.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-639"
        }
      ],
      "source": "responsibledisclosure@mattermost.com",
      "type": "Secondary"
    }
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





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.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.