Description
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.
Published: 2026-06-23
Score: 5.2 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-4c8g-jvcx-v4hv Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access
History

Tue, 23 Jun 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 23 Jun 2026 17:30:00 +0000

Type Values Removed Values Added
Description 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.
Title Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 5.2, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-23T17:54:51.686Z

Reserved: 2026-06-02T18:30:51.282Z

Link: CVE-2026-49983

cve-icon Vulnrichment

Updated: 2026-06-23T17:54:48.554Z

cve-icon NVD

No data.

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses