Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access

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.

Source published

23 Jun 2026 17:16:17 UTC

Source modified

23 Jun 2026 17:54:51 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 5.2 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N