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CVE-2026-49983— Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access

Quick assessment

Affected
denoland deno
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Deno是Deno组织开源的一个简单、现代且安全的 JavaScript 和 TypeScript 运行环境。 Deno Land Deno 2.8.1之前版本存在授权问题漏洞，该漏洞源于env权限授权不正确，process.loadEnvFile()未尊重env权限设置，可能允许具有读取dotenv文件权限的程序将文件中的密钥写入进程环境，从而绕过--deny-env限制。

CVSS 5.2 · Medium EPSS 0.14% · P3

Affected Version Matrix 1

VendorProduct Version RangeStatus
denoland deno < 2.8.1 affected
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I. Basic Information for CVE-2026-49983

Vulnerability Information
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Vulnerability Title
Deno: process.loadEnvFile() bypasses env permission checks and mutates process.env with only read access
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制不正确
Source: CVE Program / CVE List V5
Vulnerability Title
Deno Land Deno 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Deno是Deno组织开源的一个简单、现代且安全的 JavaScript 和 TypeScript 运行环境。 Deno Land Deno 2.8.1之前版本存在授权问题漏洞，该漏洞源于env权限授权不正确，process.loadEnvFile()未尊重env权限设置，可能允许具有读取dotenv文件权限的程序将文件中的密钥写入进程环境，从而绕过--deny-env限制。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
denoland deno < 2.8.1 -

II. Public POCs for CVE-2026-49983

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III. Intelligence Information for CVE-2026-49983

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Vendor Advisories for CVE-2026-49983 (1)

Same Patch Batch · denoland · 2026-06-23 · 10 CVEs total

CVE-2026-49402 8.1 HIGH Deno: Command Injection via spawnSync & spawn on Windows
CVE-2026-49440 7.4 HIGH Deno: Miller-Rabin Primality Test Allows Zero Rounds
CVE-2026-44726 7.4 HIGH Deno: TLS retry copies stale upgrade hook, risking plaintext traffic
CVE-2026-49401 7.3 HIGH Deno Permission Bypass via Unicode Normalization Mismatch on macOS (APFS)
CVE-2026-49411 6.5 MEDIUM Deno Node TCPWrap numeric hostname aliases bypass --deny-net resolved-IP deny checks
CVE-2026-49406 5.5 MEDIUM Deno: BYONM module resolution allows `package.json` main path traversal to bypass `--allow
CVE-2026-49860 5.2 MEDIUM Deno: WebSocket API sandbox bypass via missing post-DNS check
CVE-2026-49859 5.2 MEDIUM Deno: `fetch()` API sandbox bypass via missing DNS resolution check
CVE-2026-55517 4.3 MEDIUM Deno: Denial of service via non-ASCII bytes in WebSocket response headers

IV. Related Vulnerabilities

Same product: deno
Same vendor: denoland
Same weakness: CWE-863

V. Comments for CVE-2026-49983

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