# CVE-2026-49983: Deno environment permission bypass in process.loadEnvFile

Source: https://junglewise.ai/threats/cve-2026-49983-deno-environment-permission-bypass-in-process-loadenvfile  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-23. Updated: 2026-06-23  
License: CC BY 4.0 with a link back

CVE-2026-49983 · Severity: medium · CVSS 5.2 · Published 2026-06-23

Deno is a software runtime used to execute JavaScript and TypeScript applications. A security flaw in its permission system allows an application to modify environment variables even when specifically restricted from doing so. If an attacker can control a configuration file on the system, they could bypass security boundaries to inject unauthorized settings into the running program.

Technologies: [deno (crates.io)](https://junglewise.ai/threats/technologies/deno). Vendors: [crates.io](https://junglewise.ai/threats/vendors/crates-io).

## Quick answers

**Is CVE-2026-49983 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-49983 being exploited in the wild.

**How severe is CVE-2026-49983?** Medium severity, with a CVSS score of 5.2, published 23 June 2026.

**Which products and versions are affected?** deno (crates.io) <= 2.8.0, SEMVER:introduced=0,fixed=2.8.1.

**Is there a fix for CVE-2026-49983?** Yes. deno (crates.io): upgrade to 2.8.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-49983 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-49983?** Check whether you run deno (crates.io) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- deno (crates.io): upgrade to 2.8.1 or later

  ```sh
  cargo update -p deno
  ```


## Technical details

An authorization bypass exists in Deno's Node-compatible 'process.loadEnvFile()' API. While Deno normally gates environment access via the '--allow-env' or '--deny-env' flags, this specific function only validates file read permissions ('--allow-read') before writing keys from a .env file into 'process.env'. A local attacker or malicious dependency that can control a .env file can effectively bypass environment restrictions to mutate the process environment. This issue affects Deno versions 2.3.0 through 2.8.0 and is resolved in version 2.8.1.

## Affected products

- denoland Deno >= 2.3.0, < 2.8.1

## Identifiers

- CVE-2026-49983
- GHSA-4c8g-jvcx-v4hv

## Timeline

- 2026-05-27: advisory: GitHub advisory published by denoland
- 2026-06-23: disclosed: CVE published to NVD
- 2026-06-23: patched: Fix released in version 2.8.1

## References

- [https://github.com/denoland/deno/security/advisories/GHSA-4c8g-jvcx-v4hv](https://github.com/denoland/deno/security/advisories/GHSA-4c8g-jvcx-v4hv)

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