CVE-2026-49983
Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access
Impact
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 packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| rust | deno | <= 2.8.0 | 2.8.1 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Deno | Deno | from 2.3.0 before 2.8.1 |