CVE-2026-41431
Zen is a firefox-based browser. Prior to 1.19.9b, Zen Browser ships a Mozilla Application Resource (MAR) updater (org.mozilla.updater) that has had all MAR signature verification stripped from the Firefox codebase it was forked from. The MAR files served to users contain zero cryptographic signatures, and the updater binary contains zero cryptographic verification code. This eliminates the defense-in-depth that MAR signing provides. If the update server or GitHub release pipeline is compromised, arbitrary unsigned code can be delivered to all Zen users via the auto-update mechanism. This vulnerability is fixed in 1.19.9b.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
- Puntuación base: 8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.27%
- Percentil entre todas las CVEs puntuadas: 18
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1195Supply Chain Compromiseinitial access85 % - Impacto principal
T1553.006Code Signing Policy Modificationdefense impairment90 % - Impacto secundario
T1059Command and Scripting Interpreterexecution85 %
Vulnerabilidad en cadena de suministro: actualizador MAR sin verificación criptográfica permite entrega de código arbitrario si servidor o pipeline de GitHub se comprometen. Impactos: evasión de validación de código (T1553.006) y ejecución de código remoto arbitrario (T1059).
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
CWE
- CWE-347
Referencias
JSON original (NVD)
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"timestamp": "2026-05-11T18:31:13.968267Z"
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"published": "2026-05-11T18:16:34.280",
"references": [
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"value": "Zen is a firefox-based browser. Prior to 1.19.9b, Zen Browser ships a Mozilla Application Resource (MAR) updater (org.mozilla.updater) that has had all MAR signature verification stripped from the Firefox codebase it was forked from. The MAR files served to users contain zero cryptographic signatures, and the updater binary contains zero cryptographic verification code. This eliminates the defense-in-depth that MAR signing provides. If the update server or GitHub release pipeline is compromised, arbitrary unsigned code can be delivered to all Zen users via the auto-update mechanism. This vulnerability is fixed in 1.19.9b."
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"lastModified": "2026-06-17T10:46:43.050",
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