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CVE-2026-49983

5.2 · MEDIUM

Deno is a JavaScript, TypeScript, and WebAssembly runtime.

Published Jun 23, 2026CWE-863EPSS 0.14%

Overview

CVE-2026-49983 is a medium-severity vulnerability. It was published on June 23, 2026 and has a CVSS 3.1 base score of 5.2 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.2, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/denoland/deno/security/advisories/GHSA-4c8g-jvcx-v4hv

How CyberStrike helps

Frequently asked questions

What is CVE-2026-49983?

CVE-2026-49983 is a medium-severity vulnerability. It was published on June 23, 2026 and has a CVSS 3.1 base score of 5.2 (MEDIUM).

How severe is CVE-2026-49983?

This vulnerability has a CVSS 3.1 base score of 5.2, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-49983?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-49983?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-49983 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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