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

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Summary

CVECVE-2026-49983
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-23 18:18:04 UTC
Updated2026-06-23 19:34:58 UTC
DescriptionDeno 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.

Risk And Classification

Primary CVSS: v3.1 5.2 MEDIUM from [email protected]

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

Problem Types: CWE-863 | CWE-863 CWE-863: Incorrect Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.2MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
3.1CNADECLARED5.2MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Denoland Deno affected < 2.8.1 Not specified

References

ReferenceSourceLinkTags
github.com/denoland/deno/security/advisories/GHSA-4c8g-jvcx-v4hv [email protected] github.com
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