CVE-2026-49983

Published Jun 23, 2026

Last updated 2 months ago

Overview

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.
Source
security-advisories@github.com
NVD status
Analyzed
Products
deno

Risk scores

CVSS 3.1

Type
Secondary
Base score
5.2
Impact score
2.7
Exploitability score
2
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
Severity
MEDIUM

Weaknesses

security-advisories@github.com
CWE-863

Social media

Hype score
Not currently trending

Configurations

References

Sources include official advisories and independent security research.