CVE-2026-49983 json
Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access
published 2026-06-16 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-38543 , GHSA-4c8g-jvcx-v4hv , JLSEC-2026-1166
- cvss
- 5.2
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.1%
- EPSS 0.1% chance of exploitation in 30 days, percentile 3%
- public exploits
- 0
- none known
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.
Patch / fix
- crates.io deno 2.8.1
- julia Deno_jll 2.8.1+0
- deno deno 2.8.1
- deno deno_runtime 2.8.1
- deno serde_v8 2.8.1
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 4 mo ago
Exploit prediction
0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.2 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N |
| GitHub | 3.1 | 5.2 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N |
| OSV | 3.1 | 5.2 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| crates.io | deno | <2.8.1 |
2.8.1 |
| julia | Deno_jll | >=2.6.3+0, <2.8.1+0 |
2.8.1+0 |
Affected products
- denoland deno
Classification
- Weakness
-
- CWE-863 Incorrect Authorization
References
-
github.com
/denoland/deno/security/advisories/GHSA-4c8g-jvcx-v4hv
web, vendor-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-49983
advisory, web
-
github.com
/denoland/deno
package
-
github.com
/advisories/GHSA-4c8g-jvcx-v4hv
web
Sources
- CVE List CVE-2026-49983
- GitHub Advisory GHSA-4c8g-jvcx-v4hv
- NVD CVE-2026-49983
- OSV JLSEC-2026-1166
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.