{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-18756",
        "assignerOrgId": "84fe0718-d6bb-4716-a7e8-81a6d1daa869",
        "state": "PUBLISHED",
        "assignerShortName": "Fluid Attacks",
        "dateReserved": "2026-08-04T01:50:20.595Z",
        "datePublished": "2026-08-19T14:46:25.019Z",
        "dateUpdated": "2026-08-21T16:16:40.683Z"
    },
    "containers": {
        "cna": {
            "affected": [
                {
                    "defaultStatus": "unaffected",
                    "platforms": [
                        "Windows",
                        "MacOS",
                        "Linux"
                    ],
                    "product": "HumHub",
                    "repo": "https://github.com/humhub/humhub",
                    "vendor": "HumHub",
                    "versions": [
                        {
                            "status": "affected",
                            "version": "1.18.4"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "cpeMatch": [
                                {
                                    "criteria": "cpe:2.3:a:humhub:humhub:1.18.4:*:windows:*:*:*:*:*",
                                    "vulnerable": true
                                },
                                {
                                    "criteria": "cpe:2.3:a:humhub:humhub:1.18.4:*:macos:*:*:*:*:*",
                                    "vulnerable": true
                                },
                                {
                                    "criteria": "cpe:2.3:a:humhub:humhub:1.18.4:*:linux:*:*:*:*:*",
                                    "vulnerable": true
                                }
                            ],
                            "negate": false,
                            "operator": "OR"
                        }
                    ],
                    "operator": "OR"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "type": "finder",
                    "value": "Miguel Gomez"
                },
                {
                    "lang": "en",
                    "type": "finder",
                    "value": "Fluid Attacks' AI SAST Scanner"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "<span style=\"background-color: rgb(255, 255, 255);\">HumHub Community Edition 1.18.4 contains a reflected cross-site scripting vulnerability in the Space membership-request workflow. An attacker can place attacker-controlled button configuration in the </span><code>options</code><span style=\"background-color: rgb(255, 255, 255);\"> query-string parameter of </span><code>space/membership/request-membership-form</code><span style=\"background-color: rgb(255, 255, 255);\">, lure an authenticated non-member into submitting the legitimate membership request form, and cause the server to return JavaScript containing attacker-controlled code.</span><br>"
                        }
                    ],
                    "value": "HumHub Community Edition 1.18.4 contains a reflected cross-site scripting vulnerability in the Space membership-request workflow. An attacker can place attacker-controlled button configuration in the options query-string parameter of space/membership/request-membership-form, lure an authenticated non-member into submitting the legitimate membership request form, and cause the server to return JavaScript containing attacker-controlled code."
                }
            ],
            "impacts": [
                {
                    "capecId": "CAPEC-591",
                    "descriptions": [
                        {
                            "lang": "en",
                            "value": "CAPEC-591 Reflected XSS"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "attackComplexity": "LOW",
                        "attackRequirements": "PRESENT",
                        "attackVector": "NETWORK",
                        "baseScore": 7.2,
                        "baseSeverity": "HIGH",
                        "privilegesRequired": "LOW",
                        "providerUrgency": "NOT_DEFINED",
                        "subAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "LOW",
                        "subIntegrityImpact": "LOW",
                        "userInteraction": "ACTIVE",
                        "valueDensity": "NOT_DEFINED",
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N",
                        "version": "4.0",
                        "vulnAvailabilityImpact": "NONE",
                        "vulnConfidentialityImpact": "HIGH",
                        "vulnIntegrityImpact": "HIGH",
                        "vulnerabilityResponseEffort": "NOT_DEFINED"
                    },
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ]
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-79",
                            "description": "CWE-79 Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting')",
                            "lang": "en",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "84fe0718-d6bb-4716-a7e8-81a6d1daa869",
                "shortName": "Fluid Attacks",
                "dateUpdated": "2026-08-19T14:46:25.019Z"
            },
            "references": [
                {
                    "tags": [
                        "third-party-advisory"
                    ],
                    "url": "https://fluidattacks.com/es/advisories/turizo"
                },
                {
                    "tags": [
                        "product"
                    ],
                    "url": "https://github.com/humhub/humhub"
                },
                {
                    "tags": [
                        "patch"
                    ],
                    "url": "https://github.com/humhub/humhub/pull/8381"
                }
            ],
            "source": {
                "discovery": "UNKNOWN"
            },
            "title": "HumHub Community Edition 1.18.4-pl1 - Reflected XSS in Space membership request button rendering",
            "x_generator": {
                "engine": "Vulnogram 0.2.0"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-08-21T16:06:13.907685Z",
                                "id": "CVE-2026-18756",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
                                    {
                                        "Technical Impact": "total"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-08-21T16:16:40.683Z"
                }
            }
        ]
    }
}