CVE-2026-49983

Description

## Summary In Deno, 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`.** ## Am I affected? You are potentially affected if **all** of the following are true: 1. You run Deno **v2.3.0 or newer**. 2. Your program (or any dependency it imports) calls `process.loadEnvFile()` from `node:process`. 3. You rely on Deno's permission model — specifically `--deny-env`, an `--allow-env=…` allowlist, or running without granting `env` — as a security boundary. 4. The `.env` path passed to `loadEnvFile()` can be controlled or modified by a less-trusted party (untrusted input, user-writable directory, third-party dependency, etc.) and is covered by your `--allow-read` grant. If your program does not use `process.loadEnvFile()` at all, or if it already grants full `env` access, this advisory does not change your risk.

How to fix CVE-2026-49983

To remediate CVE-2026-49983, upgrade the affected package to a fixed version below.

• —upgrade to 2.8.1 or later

Is CVE-2026-49983 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (1)

• from 0, < 2.8.1