CVE-2026-48788

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{"affected": [{"affectedData": [{"product": "remark42", "vendor": "umputun", "versions": [{"status": "affected", "version": ">= 1.6.0, < 1.16.0"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Remark42 is a self-hosted comment engine for blogs, articles, or any other place where readers can add comments. Versions 1.6.0 through 1.15.0 contain a Cross-Site Scripting (XSS) vulnerability exploitable through content-type spoofing. The Remark42 image proxy fetches an arbitrary remote URL and re-serves the response from Remark42's own origin. During the download phase, the proxy determines whether the resource is an image by inspecting only the Content-Type header advertised by the remote server, never examining the actual bytes; during the serving phase, it instead derives the response Content-Type by sniffing those bytes with http.DetectContentType. An attacker can exploit this inconsistency by hosting a URL that advertises Content-Type: image/png while returning an HTML/JavaScript body: the download check accepts it as an image, the serving path sniffs the body and emits Content-Type: text/html, and the browser renders the attacker-controlled HTML/JavaScript as a document within Remark42's origin. Exploitation requires no Remark42 account on the target instance; the attacker only needs to host the malicious upstream URL and deliver the proxy link to a victim by any means, such as email, direct message, or a link on another website. This issue has been fixed in version 1.16.0."}, {"lang": "es", "value": "Remark42 es un motor de comentarios autoalojado para blogs, art\u00edculos o cualquier otro lugar donde los lectores puedan a\u00f1adir comentarios. Las versiones 1.6.0 a la 1.15.0 contienen una vulnerabilidad de Cross-Site Scripting (XSS) explotable a trav\u00e9s de la suplantaci\u00f3n de tipo de contenido. El proxy de im\u00e1genes de Remark42 obtiene una URL remota arbitraria y vuelve a servir la respuesta desde el propio origen de Remark42. Durante la fase de descarga, el proxy determina si el recurso es una imagen inspeccionando solo el encabezado Content-Type anunciado por el servidor remoto, sin examinar nunca los bytes reales; durante la fase de servicio, en su lugar, deriva el Content-Type de la respuesta detectando esos bytes con http.DetectContentType. Un atacante puede explotar esta inconsistencia alojando una URL que anuncia Content-Type: image/png mientras devuelve un cuerpo HTML/javascript_disabled: la verificaci\u00f3n de descarga lo acepta como una imagen, la ruta de servicio detecta el cuerpo y emite Content-Type: text/html, y el navegador renderiza el HTML/JavaScript controlado por el atacante como un documento dentro del origen de Remark42. La explotaci\u00f3n no requiere una cuenta de Remark42 en la instancia objetivo; el atacante solo necesita alojar la URL maliciosa de origen y entregar el enlace del proxy a una v\u00edctima por cualquier medio, como correo electr\u00f3nico, mensaje directo o un enlace en otro sitio web. Este problema ha sido solucionado en la versi\u00f3n 1.16.0."}], "id": "CVE-2026-48788", "lastModified": "2026-10-25T23:10:00.167", "metrics": {"cvssMetricV30": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.2, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N", "version": "3.0"}, "exploitabilityScore": 2.8, "impactScore": 4.7, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-48788", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-06-17T13:19:50.596883Z", "version": "2.0.3"}}]}, "published": "2026-06-17T13:20:43.490", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/umputun/remark42/commit/78d6de6bce1e961f023969da3ec8a00dd80c9ae8"}, {"source": "security-advisories@github.com", "url": "https://github.com/umputun/remark42/releases/tag/v1.16.0"}, {"source": "security-advisories@github.com", "url": "https://github.com/umputun/remark42/security/advisories/GHSA-4c8j-mgm4-qqvp"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://github.com/umputun/remark42/security/advisories/GHSA-4c8j-mgm4-qqvp"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}, {"lang": "en", "value": "CWE-436"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

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