CVE-2026-27491

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Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, a type coercion issue in a post actions API endpoint allowed non-staff users to issue warnings to other users. Warnings are a staff-only moderation feature. The vulnerability required the attacker to be a logged-in user and to send a specifically crafted request. No data exposure or privilege escalation beyond the ability to create unauthorized user warnings was possible. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available."}, {"lang": "es", "value": "Discourse es una plataforma de discusi\u00f3n de c\u00f3digo abierto. Antes de las versiones 2026.3.0-latest.1, 2026.2.1 y 2026.1.2, un problema de coerci\u00f3n de tipos en un endpoint de la API de acciones de publicaciones permit\u00eda a usuarios que no eran parte del personal emitir advertencias a otros usuarios. Las advertencias son una caracter\u00edstica de moderaci\u00f3n solo para el personal. La vulnerabilidad requer\u00eda que el atacante fuera un usuario con sesi\u00f3n iniciada y enviara una solicitud espec\u00edficamente dise\u00f1ada. No fue posible la exposici\u00f3n de datos ni la escalada de privilegios m\u00e1s all\u00e1 de la capacidad de crear advertencias de usuario no autorizadas. Las versiones 2026.3.0-latest.1, 2026.2.1 y 2026.1.2 contienen un parche. No se conocen soluciones alternativas disponibles."}], "id": "CVE-2026-27491", "lastModified": "2026-06-17T10:27:14.733", "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": "nvd@nist.gov", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 6.9, "baseSeverity": "MEDIUM", "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": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/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": "LOW", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-27491", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-03-20T20:19:52.615042Z", "version": "2.0.3"}}]}, "published": "2026-03-19T21:17:09.090", "references": [{"source": "security-advisories@github.com", "tags": ["Patch"], "url": "https://github.com/discourse/discourse/commit/60a588f4da4ab0feceb2c44787d4261b4f8757be"}, {"source": "security-advisories@github.com", "tags": ["Patch"], "url": "https://github.com/discourse/discourse/commit/d3cb203feabc46d765ecb91f348613a2bd531b89"}, {"source": "security-advisories@github.com", "tags": ["Patch"], "url": "https://github.com/discourse/discourse/commit/f5fef73827da7520efc517357bd2a6bab35d7886"}, {"source": "security-advisories@github.com", "tags": ["Vendor Advisory"], "url": "https://github.com/discourse/discourse/security/advisories/GHSA-xq37-5fvf-4m4j"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-862"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2026.1.0-latest,2026.1.2)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[2026.2.0-latest,2026.2.1)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "2026.3.0-latest"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "discourse", "source": "cna", "vendor": "discourse"}, "product": "discourse", "vendor": "discourse"}], "analysis": {"en": {"generated_at": "2026-03-25T03:25:40.282833+00:00", "value": {"mitigation_remediation": ["Upgrade to any patched release 2026.3.0\u2011latest.1, 2026.2.1, or 2026.1.2 or later", "Verify after upgrading that only staff members can trigger the warning endpoint by attempting the call with a non\u2011staff account", "Monitor logs for unusual warning creation attempts by non\u2011staff users"], "summary": {"action": "Patch", "impact": "Unauthorized Warning Issuance"}, "threat_synthesis": {"affected_systems": "The issue affects all Discourse releases earlier than 2026.3.0\u2011latest.1, 2026.2.1, and 2026.1.2, in which non\u2011staff users can trigger the warning endpoint. The flaw is limited to authenticated users; unauthenticated visitors cannot initiate the attack. The affected product is the open\u2011source Discourse discussion platform.", "description_and_impact": "A type coercion bug in Discourse\u2019s post\u2011actions API allows a logged\u2011in user who is not staff to craft a request that creates a warning against another user. Because warnings are intended for moderation staff, this flaw gives non\u2011staff members a limited moderation privilege, potentially affecting user reputation and platform trust. The vulnerability does not reveal data or provide full privilege escalation beyond warning creation.", "risk_and_exploitability": "The CVSS score of 6.9 indicates a medium severity risk. EPSS shows an exploitation likelihood below 1\u202f% and the vulnerability is not listed in CISA\u2019s KEV catalog, suggesting limited known exploitation. Based on the description, the attack vector is remote via the API and requires an authenticated user to send a crafted request, meaning that a legitimate user with an account can abuse the warning system, though no additional system resources are impacted."}}}}, "created": "2026-03-20T08:56:08.149961+00:00", "updated": "2026-03-25T11:54:57.350959+00:00", "vendors": ["discourse", "discourse$PRODUCT$discourse"]}