Vulnerability · Published Jun 23, 2026 · Assigned by GitHub_M
CVE-2026-49983Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access
Medium 5.2
In plain English
A medium-severity incorrect authorization in deno from denoland. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities).
Official 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.
Affected products (as reported)
Weakness: CWE-863 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
References
- https://github.com/denoland/deno/security/advisories/GHSA-4c8g-jvcx-v4hv x_refsource_CONFIRM