{"id":"CVE-2026-49983","aliases":["GHSA-4c8g-jvcx-v4hv"],"url":"https://o3.security/vulnerability/CVE-2026-49983","summary":"Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access","details":"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.","published":"2026-06-23T17:16:17.026Z","modified":"2026-08-12T03:51:14.034751377Z","cvss":{"score":5.2,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N"},"epss":{"score":0.0014,"percentile":0.03629,"asOf":"2026-09-01"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"crates.io","name":"deno","fixedVersion":"2.8.1"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49983.json"},{"type":"ADVISORY","url":"https://github.com/denoland/deno/security/advisories/GHSA-4c8g-jvcx-v4hv"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49983"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:14.034751377Z"}}