{"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"}}]}}