CVE-2026-49983

Summary

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.

Affected Software

Weaknesses

• CWE-863: CWE-863: Incorrect Authorization

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: partial

References

• https://github.com/denoland/deno/security/advisories/GHSA-4c8g-jvcx-v4hv

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