@cyclonedx/cdxgen: Docker registry auth substring match forwards credentials to a different registry

Summary

# Docker registry auth substring match forwards credentials to a different registry

## Repository

`cdxgen/cdxgen`

## Affected product/package

- Ecosystem: npm - Package: `@cyclonedx/cdxgen` - Reviewed tree version: `12.3.3` - Reviewed commit: `b1e179869fd7c6032c3d483c3f7bd4d7154ec22b` - Affected file: `lib/managers/docker.js` - Affected from: v9.9.5

The Single Executable Applications (SEA) binaries and container images are also affected.

## Weakness

CWE-522 / CWE-346.

## Summary

When cdxgen scans or pulls container images through the Docker daemon API, it builds an `X-Registry-Auth` header from Docker credentials in `DOCKER_CONFIG/config.json`. The credential selection logic matches configured registry keys with substring checks:

```js if (forRegistry && !serverAddress.includes(forRegistry)) { continue; } ```

This is not an origin-safe registry comparison. For example, credentials configured for `private-registry.example.com` are selected for a requested image under `registry.example.com`, because:

```js "private-registry.example.com".includes("registry.example.com") === true ```

The selected credentials are then serialized into `X-Registry-Auth` for the Docker API pull request targeting the requested registry.

## Reproduction

Use the attached/local proof:

```sh node submissions/github-gsa/cdxgen-docker-registry-auth-substring-forwarding/evidence/cdxgen_docker_registry_auth_substring_probe.mjs ```

The proof is fully local. It creates a temporary Docker config containing credentials for `private-registry.example.com`, starts a localhost mock Docker API endpoint, sets `DOCKER_HOST` to that endpoint, then calls cdxgen's exported Docker request path for a pull from `registry.example.com`.

Observed vulnerable output:

```json { "decision": "GO", "dockerConfigAuthHost": "private-registry.example.com", "requestedRegistry": "registry.example.com", "substringMatch": true, "dockerApiUrl": "/images/create?fromImage=registry.example.com/team/app:latest", "headerPresent": true, "decodedHeader": { "username": "trusted-user", "password": "trusted-pass", "serveraddress": "private-registry.example.com" } } ```

## Impact

If an operator has Docker credentials for a private registry and uses cdxgen to scan an image from a different registry whose hostname is a substring of that private registry hostname, cdxgen can attach the private registry credentials to the Docker pull request for the different registry.

In a realistic attack, an attacker who controls or can observe the requested registry can induce a victim to scan an image from that registry. The Docker daemon API receives an `X-Registry-Auth` payload containing credentials for the victim's private registry but associated with the attacker-requested pull. This is a credential forwarding/misbinding issue in cdxgen's container image handling.

## References

Functions `normalizeRegistryHost` and `registriesMatch` added to normalize and perform strict host matching.

Fix PR: https://github.com/cdxgen/cdxgen/pull/3964

Researcher: Francesco SabiuResearcher: Francesco Sabiu