GitHub Advisoryadvisory · crates.io
GHSA-7w8p-chxq-2789 Deno.env.toObject() ignores the variables listed in --deny-env and returns all environment variables
MEDIUM
Official page ↗
- Aliases
- CVE-2025-48934
- Ecosystem
- crates.io
- Packages
- deno, deno_runtime
- Severity
- Moderate
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- Weaknesses
- CWE-201
- Reviewed
- 2025-06-04
Affected packages
• crates.io deno: < 2.1.13 → fixed in 2.1.13
• crates.io deno: >= 2.2.0, < 2.2.13 → fixed in 2.2.13
• crates.io deno_runtime: < 0.212.0 → fixed in 0.212.0
Description
Summary
The Deno.env.toObject method ignores any variables listed in the `--deny-env` option of the `deno run` command. When looking at the documentation of the `--deny-env` option this might lead to a false impression that variables listed in the option are impossible to read.
PoC
```
export AWS_SECRET_ACCESS_KEY=my-secret-aws-key
Works as expected. The program stops with a "NotCapable" error message
echo 'console.log(Deno.env.get("AWS_SECRET_ACCESS_KEY"));' | deno run \
--allow-env \
--deny-env=AWS_ACCESS_KEY_ID,AWS_SECRET_ACCESS_KEY -
All enviroment variables are printed and the --deny-env list is completely disregarded
echo 'console.log(Deno.env.toObject());' | deno run \
--allow-env \
--deny-env=AWS_ACCESS_KEY_ID,AWS_SECRET_ACCESS_KEY -
```
The first example using `get` exits with the following error:
```
error: Uncaught (in promise) NotCapable: Requires env access to "AWS_SECRET_ACCESS_KEY", run again with the --allow-env flag
console.log(Deno.env.get("AWS_SECRET_ACCESS_KEY"));
^
at Object.getEnv [as get] (ext:deno_os/30_os.js:124:10)
at file:///$deno$stdin.mts:1:22
```
The second example using `toObject` prints all environment variables:
```
[Object: null prototype] {
...
AWS_SECRET_ACCESS_KEY: "my-secret-aws-key",
...
}
```
Impact
Software relying on the combination of both flags to allow access to most environment variables except a few sensitive ones will be vulnerable to malicious code trying to steal secrets using the Deno.env.toObject() method.
Related
Alias · CVE (1)
- CVE-2025-48934 Deno is a JavaScript, TypeScript, and WebAssembly runtime. vulnerability
Weakness · CWE (1)
- CWE-201 Insertion of Sensitive Information Into Sent Data weakness
References
- https://github.com/denoland/deno/security/advisories/GHSA-7w8p-chxq-2789 web
- https://nvd.nist.gov/vuln/detail/CVE-2025-48934 advisory
- https://github.com/denoland/deno/pull/29079 web
- https://github.com/denoland/deno/commit/2959e083912420988066a001c2b2d6732a1b562f web
- https://github.com/denoland/deno/commit/946ccda1aa19a00c478a5e6826b75053b050d753 web
- https://docs.deno.com/api/deno/~/Deno.Env.toObject web
- https://docs.deno.com/runtime/fundamentals/security/#environment-variables web
- https://github.com/denoland/deno package