CVE-2026-30834: Pinchtab SSRF Vulnerability

CVE-2026-30834 Overview

CVE-2026-30834 is a Server-Side Request Forgery (SSRF) vulnerability affecting PinchTab, a standalone HTTP server designed to give AI agents direct control over a Chrome browser. The vulnerability exists in the /download endpoint and allows any user with API access to induce the PinchTab server to make requests to arbitrary URLs, including internal network services and local system files. Critically, the vulnerability enables exfiltration of full response content, potentially exposing sensitive internal resources.

Critical Impact

Attackers can leverage this SSRF vulnerability to access internal network services, read local system files via file:// protocol, and exfiltrate sensitive data from systems that should not be accessible from external networks.

Affected Products

• PinchTab versions prior to 0.7.7
• PinchTab HTTP server deployments with exposed API access
• AI agent integrations using vulnerable PinchTab instances

Discovery Timeline

• 2026-03-07 - CVE-2026-30834 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2026-30834

Vulnerability Analysis

This Server-Side Request Forgery vulnerability resides in the /download endpoint of PinchTab's HTTP server. The endpoint fails to properly validate and restrict the URLs that can be requested, allowing attackers to abuse the server as a proxy to reach internal resources.

The vulnerability is classified under CWE-918 (Server-Side Request Forgery), which describes flaws where a web application fetches remote resources based on user-supplied URLs without adequate validation. In this case, the PinchTab server processes arbitrary URLs passed to the /download endpoint, making outbound requests on behalf of the attacker.

The attack can be executed remotely over the network without requiring user interaction or elevated privileges. The primary impact is confidentiality compromise, as attackers can read responses from internal services, cloud metadata endpoints, and potentially local files.

Root Cause

The root cause of this vulnerability is insufficient URL validation in the /download endpoint handler. The endpoint accepts user-controlled URL parameters without implementing proper allow-lists or deny-lists to restrict which hosts and protocols can be accessed. This allows attackers to specify internal IP addresses (e.g., 127.0.0.1, 169.254.169.254), private network ranges, and potentially file:// URLs to access local system resources.

Attack Vector

The attack vector is network-based, requiring only API access to the PinchTab server. An attacker can craft malicious requests to the /download endpoint, specifying internal URLs as the target. The server then makes the request and returns the full response content to the attacker.

Common SSRF attack patterns applicable to this vulnerability include:

• Accessing cloud metadata services (AWS, GCP, Azure) to steal credentials
• Scanning internal network services and ports
• Reading local configuration files via file:// protocol
• Bypassing firewall restrictions to reach protected internal APIs

The vulnerability allows full response exfiltration, meaning attackers receive the complete content of the requested resource, not just confirmation of its existence.

Detection Methods for CVE-2026-30834

Indicators of Compromise

• Unusual outbound requests from the PinchTab server to internal IP ranges (10.x.x.x, 172.16.x.x, 192.168.x.x)
• Requests to cloud metadata endpoints such as 169.254.169.254
• Access logs showing requests to the /download endpoint with internal URLs or file:// URIs
• Unexpected data exfiltration patterns from the PinchTab server process

Detection Strategies

• Monitor PinchTab server logs for requests to the /download endpoint containing internal hostnames or IP addresses
• Implement network-level monitoring for outbound connections from PinchTab to internal services
• Configure alerting for access attempts to cloud metadata services from application servers
• Deploy web application firewall rules to inspect and block suspicious URL parameters

Monitoring Recommendations

• Enable verbose logging on the PinchTab server to capture all /download endpoint requests with full URL parameters
• Implement network segmentation monitoring to detect lateral movement attempts via SSRF
• Set up anomaly detection for unusual outbound traffic patterns from PinchTab deployments
• Review API access logs for unauthorized or anomalous client activity

How to Mitigate CVE-2026-30834

Immediate Actions Required

• Upgrade PinchTab to version 0.7.7 or later immediately
• Restrict API access to the PinchTab server using authentication and authorization controls
• Implement network segmentation to limit what internal resources the PinchTab server can reach
• Review access logs for evidence of exploitation attempts

Patch Information

The vendor has addressed this vulnerability in PinchTab version 0.7.7. Organizations should upgrade to this version or later to remediate the SSRF vulnerability in the /download endpoint. For detailed information about the security fix, refer to the GitHub Security Advisory GHSA-rw8p-c6hf-q3pg.

Workarounds

• Restrict network access from the PinchTab server to only required external resources using firewall rules
• Implement a reverse proxy with URL filtering in front of PinchTab to block requests with internal URLs
• Disable or restrict access to the /download endpoint if not required for operations
• Use network-level controls to block PinchTab from accessing cloud metadata services and internal networks

# Example: Network firewall rules to restrict PinchTab outbound access
# Block access to internal networks from PinchTab server
iptables -A OUTPUT -s <pinchtab_server_ip> -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -s <pinchtab_server_ip> -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -s <pinchtab_server_ip> -d 192.168.0.0/16 -j DROP
iptables -A OUTPUT -s <pinchtab_server_ip> -d 169.254.169.254 -j DROP