CVE-2026-49983

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, environment access is gated by the env permission. You can deny it with --deny-env, or restrict it to a specific allowlist with --allow-env=FOO,BAR. The expectation is that a program running without env permission cannot change process.env. process.loadEnvFile() (the Node-compatible API for loading variables from a .env file) does not honor this. It only checks that the program has read permission for the dotenv file, then writes every key in that file into the process environment — even when env access is denied. In effect, --allow-read plus a writable or attacker-controlled .env file is enough to defeat --deny-env. This vulnerability is fixed in 2.8.1.

CVSS v3 5.2 MEDIUM

5.2^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.0 / Impact : 2.7

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/denoland/deno/security/advisories/GHSA-4c8g-jvcx-v4hv	Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:deno:deno:*:*:*:*:*:*:*:*

History

25 Oct 2026, 23:10

Type	Values Removed	Values Added
Summary		(es) Deno es un entorno de ejecución de JavaScript, TypeScript y WebAssembly. Antes de la versión 2.8.1, el acceso al entorno está controlado por el permiso env. Se puede denegar con --deny-env, o restringirlo a una lista de permitidos específica con --allow-env=FOO,BAR. La expectativa es que un programa que se ejecuta sin el permiso env no pueda cambiar process.env. process.loadEnvFile() (la API compatible con Node para cargar variables de un archivo .env) no respeta esto. Solo verifica que el programa tenga permiso de lectura para el archivo dotenv, luego escribe cada clave de ese archivo en el entorno del proceso, incluso cuando el acceso env está denegado. En efecto, --allow-read más un archivo .env escribible o controlado por el atacante es suficiente para eludir --deny-env. Esta vulnerabilidad está corregida en la versión 2.8.1.

Information

Published : 2026-06-23 18:18

Updated : 2026-10-25 23:10

NVD link : CVE-2026-49983

Mitre link : CVE-2026-49983

CVE.ORG link : CVE-2026-49983

JSON object : View

Products Affected

deno

deno

CWE

CWE-863

Incorrect Authorization

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