Vulnerability-Lookup

FKIE_CVE-2026-28282

Vulnerability from fkie_nvd - Published: 2026-03-19 22:16 - Updated: 2026-06-17 10:28

Severity

6.5 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Summary

Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have a security flaw in the discourse-policy plugin which allowed a user with policy creation permission to gain membership access to any private/restricted groups. Once membership to a private/restricted group has been obtained, the user will be able to read private topics that only the group has access to. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, review all policies for the use of `add-users-to-group` and temporarily remove the attribute from the policy. Alternatively, disable the discourse-policy plugin by disabling the `policy_enabled` site setting.

References

URL	Tags
security-advisories@github.com	https://github.com/discourse/discourse/commit/64e2514ac17046cfaa8bc68a3c5140bc40736add	Patch
security-advisories@github.com	https://github.com/discourse/discourse/commit/c14b8a4cc5fc94e4839a83c5d55765897589f45b	Patch
security-advisories@github.com	https://github.com/discourse/discourse/commit/dcde9de530f515e88f99957056ffbcc2e1e03951	Patch
security-advisories@github.com	https://github.com/discourse/discourse/security/advisories/GHSA-6cc8-x3rm-j5pf	Vendor Advisory

Impacted products

Vendor	Product	Version
discourse	discourse	*
discourse	discourse	*
discourse	discourse	2026.3.0

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "discourse",
          "vendor": "discourse",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 2026.1.0-latest, \u003c 2026.1.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.2.0-latest, \u003c 2026.2.1"
            },
            {
              "status": "affected",
              "version": "= 2026.3.0-latest"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "4BE96625-3609-410C-B41E-4A824C1A57C0",
              "versionEndExcluding": "2026.1.2",
              "versionStartIncluding": "2026.1.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "FD31CF04-CF2F-4FB9-8880-9243BC7671A7",
              "versionEndExcluding": "2026.2.1",
              "versionStartIncluding": "2026.2.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:discourse:discourse:2026.3.0:*:*:*:latest:*:*:*",
              "matchCriteriaId": "E3FE9277-4F6B-4FD0-991F-F0FB8D226E1C",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have a security flaw in the discourse-policy plugin which allowed a user with policy creation permission to gain membership access to any private/restricted groups. Once membership to a private/restricted group has been obtained, the user will be able to read private topics that only the group has access to. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, review all policies for the use of `add-users-to-group` and temporarily remove the attribute from the policy. Alternatively, disable the discourse-policy plugin by disabling the `policy_enabled` site setting."
    },
    {
      "lang": "es",
      "value": "Discourse es una plataforma de discusi\u00f3n de c\u00f3digo abierto. Las versiones anteriores a 2026.3.0-latest.1, 2026.2.1 y 2026.1.2 tienen una falla de seguridad en el plugin discourse-policy que permit\u00eda a un usuario con permiso de creaci\u00f3n de pol\u00edticas obtener acceso de membres\u00eda a cualquier grupo privado/restringido. Una vez que se ha obtenido la membres\u00eda a un grupo privado/restringido, el usuario podr\u00e1 leer temas privados a los que solo el grupo tiene acceso. Las versiones 2026.3.0-latest.1, 2026.2.1 y 2026.1.2 contienen un parche. Como soluci\u00f3n alternativa, revise todas las pol\u00edticas para el uso de \u0027add-users-to-group\u0027 y elimine temporalmente el atributo de la pol\u00edtica. Alternativamente, deshabilite el plugin discourse-policy deshabilitando la configuraci\u00f3n del sitio \u0027policy_enabled\u0027."
    }
  ],
  "id": "CVE-2026-28282",
  "lastModified": "2026-06-17T10:28:25.610",
  "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": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 2.3,
          "baseSeverity": "LOW",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "LOW",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-28282",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-03-20T17:00:56.189009Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-03-19T22:16:31.317",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/discourse/discourse/commit/64e2514ac17046cfaa8bc68a3c5140bc40736add"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/discourse/discourse/commit/c14b8a4cc5fc94e4839a83c5d55765897589f45b"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/discourse/discourse/commit/dcde9de530f515e88f99957056ffbcc2e1e03951"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Vendor Advisory"
      ],
      "url": "https://github.com/discourse/discourse/security/advisories/GHSA-6cc8-x3rm-j5pf"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-863"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

CVE-2026-28282 (GCVE-0-2026-28282)

Vulnerability from cvelistv5 – Published: 2026-03-19 21:45 – Updated: 2026-03-20 18:10

Title

Discourse vulnerable to group membership addition permission bypass via discourse-policy plugin

Summary

Severity

2.3 (Low)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-03-20 17:00 UTC

CWE

CWE-863 - Incorrect Authorization

Assigner

GitHub_M mitre root

References

4 references

URL	Tags
https://github.com/discourse/discourse/security/a…	x_refsource_CONFIRM
https://github.com/discourse/discourse/commit/64e…	x_refsource_MISC
https://github.com/discourse/discourse/commit/c14…	x_refsource_MISC
https://github.com/discourse/discourse/commit/dcd…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
discourse	discourse	Affected: >= 2026.1.0-latest, < 2026.1.2 Affected: >= 2026.2.0-latest, < 2026.2.1 Affected: = 2026.3.0-latest

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-28282",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-20T17:00:56.189009Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-20T18:10:26.922Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "discourse",
          "vendor": "discourse",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 2026.1.0-latest, \u003c 2026.1.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 2026.2.0-latest, \u003c 2026.2.1"
            },
            {
              "status": "affected",
              "version": "= 2026.3.0-latest"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have a security flaw in the discourse-policy plugin which allowed a user with policy creation permission to gain membership access to any private/restricted groups. Once membership to a private/restricted group has been obtained, the user will be able to read private topics that only the group has access to. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. As a workaround, review all policies for the use of `add-users-to-group` and temporarily remove the attribute from the policy. Alternatively, disable the discourse-policy plugin by disabling the `policy_enabled` site setting."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 2.3,
            "baseSeverity": "LOW",
            "privilegesRequired": "LOW",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-863",
              "description": "CWE-863: Incorrect Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-19T21:48:54.093Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/discourse/discourse/security/advisories/GHSA-6cc8-x3rm-j5pf",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/discourse/discourse/security/advisories/GHSA-6cc8-x3rm-j5pf"
        },
        {
          "name": "https://github.com/discourse/discourse/commit/64e2514ac17046cfaa8bc68a3c5140bc40736add",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/commit/64e2514ac17046cfaa8bc68a3c5140bc40736add"
        },
        {
          "name": "https://github.com/discourse/discourse/commit/c14b8a4cc5fc94e4839a83c5d55765897589f45b",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/commit/c14b8a4cc5fc94e4839a83c5d55765897589f45b"
        },
        {
          "name": "https://github.com/discourse/discourse/commit/dcde9de530f515e88f99957056ffbcc2e1e03951",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/discourse/discourse/commit/dcde9de530f515e88f99957056ffbcc2e1e03951"
        }
      ],
      "source": {
        "advisory": "GHSA-6cc8-x3rm-j5pf",
        "discovery": "UNKNOWN"
      },
      "title": "Discourse vulnerable to group membership addition permission bypass via discourse-policy plugin"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-28282",
    "datePublished": "2026-03-19T21:45:13.648Z",
    "dateReserved": "2026-02-26T01:52:58.735Z",
    "dateUpdated": "2026-03-20T18:10:26.922Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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.