CVE-2026-40611
Let's Encrypt client and ACME library written in Go (Lego). Prior to 4.34.0, the webroot HTTP-01 challenge provider in lego is vulnerable to arbitrary file write and deletion via path traversal. A malicious ACME server can supply a crafted challenge token containing ../ sequences, causing lego to write attacker-influenced content to any path writable by the lego process. This vulnerability is fixed in 4.34.0.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Puntuación base: 8.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.55%
- Percentil entre todas las CVEs puntuadas: 44
- 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
T1203Exploitation for Client Executionexecution85 % - Impacto principal
T1565.001Stored Data Manipulationimpact90 % - Impacto secundario
T1070.004File Deletionstealth80 %
UI:R requiere interacción del usuario (procesar challenge ACME). Path traversal (CWE-22) permite escribir/borrar archivos arbitrarios, impactando integridad y disponibilidad de datos.
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-22
- CWE-22
Referencias
- https://github.com/go-acme/lego/security/advisories/GHSA-qqx8-2xmm-jrv8
- https://access.redhat.com/errata/RHSA-2026:21772
- https://access.redhat.com/security/cve/CVE-2026-40611
- https://bugzilla.redhat.com/show_bug.cgi?id=2460233
- https://github.com/go-acme/lego/security/advisories/GHSA-qqx8-2xmm-jrv8
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40611.json
JSON original (NVD)
Mostrar
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