CVE-2026-27456

{"id": "CVE-2026-27456", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-27456", "role": "CISA Coordinator", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-04-06T15:38:42.794607Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 4.7, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "NONE", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}, "impactScore": 3.6, "exploitabilityScore": 1.0}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "util-linux", "product": "util-linux", "versions": [{"status": "affected", "version": "< 2.41.4"}]}]}], "published": "2026-04-03T22:16:25.400", "references": [{"url": "https://github.com/util-linux/util-linux/commit/5e390467b26a3cf3fecc04e1a0d482dff3162fc4", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/util-linux/util-linux/releases/tag/v2.41.4", "tags": ["Product"], "source": "security-advisories@github.com"}, {"url": "https://github.com/util-linux/util-linux/security/advisories/GHSA-qq4x-vfq4-9h9g", "tags": ["Exploit", "Vendor Advisory"], "source": "security-advisories@github.com"}, {"url": "https://github.com/util-linux/util-linux/security/advisories/GHSA-qq4x-vfq4-9h9g", "tags": ["Exploit", "Vendor Advisory"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-59"}, {"lang": "en", "value": "CWE-269"}, {"lang": "en", "value": "CWE-367"}]}, {"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-367"}]}], "descriptions": [{"lang": "en", "value": "util-linux is a random collection of Linux utilities. Prior to version 2.41.4, a TOCTOU (Time-of-Check-Time-of-Use) vulnerability has been identified in the SUID binary /usr/bin/mount from util-linux. The mount binary, when setting up loop devices, validates the source file path with user privileges via fork() + setuid() + realpath(), but subsequently re-canonicalizes and opens it with root privileges (euid=0) without verifying that the path has not been replaced between both operations. Neither O_NOFOLLOW, nor inode comparison, nor post-open fstat() are employed. This allows a local unprivileged user to replace the source file with a symlink pointing to any root-owned file or device during the race window, causing the SUID binary to open and mount it as root. Exploitation requires an /etc/fstab entry with user,loop options whose path points to a directory where the attacker has write permission, and that /usr/bin/mount has the SUID bit set (the default configuration on virtually all Linux distributions). The impact is unauthorized read access to root-protected files and block devices, including backup images, disk volumes, and any file containing a valid filesystem. This issue has been patched in version 2.41.4."}, {"lang": "es", "value": "util-linux es una colecci\u00f3n aleatoria de utilidades de Linux. Antes de la versi\u00f3n 2.41.4, se ha identificado una vulnerabilidad TOCTOU (Time-of-Check-Time-of-Use) en el binario SUID /usr/bin/mount de util-linux. El binario mount, al configurar dispositivos de bucle, valida la ruta del archivo de origen con privilegios de usuario a trav\u00e9s de fork() + setuid() + realpath(), pero posteriormente la vuelve a canonizar y la abre con privilegios de root (euid=0) sin verificar que la ruta no haya sido reemplazada entre ambas operaciones. No se emplean ni O_NOFOLLOW, ni la comparaci\u00f3n de inodos, ni fstat() posterior a la apertura. Esto permite a un usuario local sin privilegios reemplazar el archivo de origen con un enlace simb\u00f3lico que apunte a cualquier archivo o dispositivo propiedad de root durante la ventana de carrera, haciendo que el binario SUID lo abra y monte como root. La explotaci\u00f3n requiere una entrada en /etc/fstab con las opciones user,loop cuya ruta apunte a un directorio donde el atacante tenga permiso de escritura, y que /usr/bin/mount tenga el bit SUID establecido (la configuraci\u00f3n predeterminada en pr\u00e1cticamente todas las distribuciones de Linux). El impacto es el acceso de lectura no autorizado a archivos protegidos por root y dispositivos de bloque, incluyendo im\u00e1genes de respaldo, vol\u00famenes de disco y cualquier archivo que contenga un sistema de archivos v\u00e1lido. Este problema ha sido parcheado en la versi\u00f3n 2.41.4."}], "lastModified": "2026-07-24T22:10:00.140", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:kernel:util-linux:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "A0F464C1-2AC1-4B59-B522-89DD9D072C7F", "versionEndExcluding": "2.41.4"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}