Skip to main content

Boteraser | Website and Server Security Solutions

🛡️ JLSEC-2026-1166 — deno-jll (CVE-2026-49983)

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access

Summary

In Deno, 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.**

Am I affected?

You are potentially affected if all of the following are true:

1. You run Deno v2.3.0 or newer.

2. Your program (or any dependency it imports) calls process.loadEnvFile()

from node:process.

3. You rely on Deno's permission model — specifically --deny-env, an

--allow-env=… allowlist, or running without granting env — as a

security boundary.

4. The .env path passed to loadEnvFile() can be controlled or modified by

a less-trusted party (untrusted input, user-writable directory, third-party

dependency, etc.) and is covered by your --allow-read grant.

If your program does not use process.loadEnvFile() at all, or if it already

grants full env access, this advisory does not change your risk.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality low, integrity low, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Changed — a successful attack reaches components beyond the vulnerable one.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: None.

Affected software

JLSEC-2026-1166 is recorded against 1 package.

  • deno-jll

Timeline and source

Published on 5 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
github.com (Web)
nvd.nist.gov (Web)

Other advisories for this package

deno-jll has other advisories on record. If you are patching this one, these are worth checking on the same host:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-08-05
Updated 2026-08-20
Modified 2026-08-05
Fix URL N/A

Affected Packages

Software From version Fixed in
deno-jll — —

Similar Threats

Free Vulnerability Check

Is your site affected by JLSEC-2026-1166?

BotEraser helps you identify potentially vulnerable plugins and themes by checking your installation against JLSEC-2026-1166 and other known CVE records.

Scan My Site Free →

No credit card required  ·  Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

Browse related advisories

All advisoriesJlsecJlsec 2026
✓