CVE-2026-49983
Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access
- State
- Published
- Severity
- 5.2 Medium
- Published
- Jun 23, 2026
- Updated
- Jun 23, 2026
- Reserved
- Jun 2, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.2 Medium | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N | GitHub_M |
Weaknesses
- CWE-863 Incorrect Authorization
Affected Products
| Product | Versions |
|---|---|
denodenoland |
|
References
Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.