CVE-2026-4907 Overview
A Server-Side Request Forgery (SSRF) vulnerability has been identified in Page-Replica's Page Replica application. The vulnerability exists in the sitemap.fetch function within the /sitemap endpoint component. By manipulating the url argument, remote attackers can force the server to make requests to arbitrary internal or external destinations, potentially exposing sensitive internal resources or enabling further attacks against internal infrastructure.
Critical Impact
Remote attackers can exploit this SSRF vulnerability to access internal network resources, potentially bypassing firewalls and security controls to reach sensitive systems not intended to be publicly accessible.
Affected Products
- Page-Replica Page Replica (up to commit e4a7f52e75093ee318b4d5a9a9db6751050d2ad0)
- All versions prior to the identified vulnerable commit
- Rolling release versions without specific version tracking
Discovery Timeline
- 2026-03-27 - CVE-2026-4907 published to NVD
- 2026-03-30 - Last updated in NVD database
Technical Details for CVE-2026-4907
Vulnerability Analysis
This vulnerability is classified as CWE-918 (Server-Side Request Forgery). The weakness occurs when the application's /sitemap endpoint accepts a user-controlled url parameter and uses it to make server-side HTTP requests without proper validation. This allows attackers to craft malicious requests that force the vulnerable server to interact with arbitrary destinations.
SSRF vulnerabilities in sitemap functionality are particularly dangerous because these endpoints are often designed to fetch and process remote content, making them natural targets for exploitation. The affected sitemap.fetch function appears to lack sufficient validation of the target URL, enabling attackers to specify internal network addresses, cloud metadata endpoints, or other sensitive resources.
The vendor was contacted early about this disclosure but did not respond. Page-Replica uses a rolling release strategy, so specific version numbers for affected or patched releases are not available.
Root Cause
The root cause is insufficient input validation of the url parameter passed to the sitemap.fetch function in the /sitemap endpoint. The application fails to properly sanitize or restrict the destination URLs that can be requested, allowing attackers to specify arbitrary targets including internal network resources, localhost services, and cloud metadata endpoints.
Attack Vector
The attack can be carried out remotely over the network. An authenticated attacker with low privileges can exploit this vulnerability by sending crafted HTTP requests to the /sitemap endpoint with a manipulated url parameter. The exploitation mechanism involves:
- Attacker identifies the vulnerable /sitemap endpoint
- Attacker crafts a request with a malicious url parameter pointing to internal resources (e.g., http://localhost:8080/admin, http://169.254.169.254/latest/meta-data/)
- The server-side sitemap.fetch function processes the request and makes the HTTP call to the attacker-specified destination
- Internal responses or error messages are returned to the attacker, potentially leaking sensitive information
The exploit for this vulnerability has been publicly disclosed. Technical details can be found in the GitHub CVE Discovery Resource.
Detection Methods for CVE-2026-4907
Indicators of Compromise
- Unusual outbound HTTP requests from the application server to internal IP addresses (e.g., 127.0.0.1, 10.x.x.x, 172.16.x.x, 192.168.x.x)
- Requests to cloud metadata endpoints such as 169.254.169.254 originating from the Page-Replica application
- HTTP requests to the /sitemap endpoint with suspicious url parameters containing internal hostnames or IP addresses
- Unexpected network connections to internal services from the web application tier
Detection Strategies
- Implement web application firewall (WAF) rules to detect and block requests containing internal IP addresses or reserved hostnames in URL parameters
- Deploy network monitoring to detect anomalous outbound connections from web application servers to internal network segments
- Configure SIEM alerts for /sitemap endpoint access patterns with URL parameters pointing to private IP ranges
Monitoring Recommendations
- Enable detailed access logging for the /sitemap endpoint to capture all url parameter values
- Monitor for DNS lookups to internal hostnames originating from the web application tier
- Set up alerts for any HTTP responses containing cloud metadata or internal service responses
- Track failed connection attempts to internal services that may indicate SSRF probing
How to Mitigate CVE-2026-4907
Immediate Actions Required
- Restrict or disable access to the /sitemap endpoint if not required for production functionality
- Implement network-level controls to prevent the application server from making requests to internal IP ranges
- Deploy a web application firewall with SSRF detection rules to filter malicious requests
- Review and audit all instances of the sitemap.fetch function for proper URL validation
Patch Information
No official patch has been released by the vendor. The vendor was contacted early about this disclosure but did not respond. Since Page-Replica uses a rolling release strategy, organizations should monitor the project repository for updates that address this vulnerability.
For tracking and additional context, refer to:
Workarounds
- Implement an allowlist of permitted URL schemes and domains for the url parameter
- Deploy network segmentation to prevent the application server from reaching sensitive internal resources
- Use a proxy or intermediate service to handle external URL fetches with strict validation
- Consider disabling the vulnerable /sitemap endpoint entirely until a fix is available
Organizations should implement strict URL validation that:
- Only allows specific URL schemes (e.g., http and https)
- Blocks requests to private IP address ranges and localhost
- Validates domain names against an allowlist of trusted external sources
- Blocks requests to cloud metadata IP addresses (169.254.169.254)
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
