CVE-2025-7777: Mirror-Registry XSS Vulnerability

CVE-2025-7777 Overview

CVE-2025-7777 is an open redirect vulnerability in the Red Hat mirror-registry component. The registry fails to properly sanitize the HTTP Host header in incoming requests. An attacker who controls the Host header value can force the application to generate URLs and redirects pointing to attacker-controlled domains. This behavior enables phishing campaigns and credential harvesting against users who trust the legitimate registry hostname. The weakness is classified under CWE-601: URL Redirection to Untrusted Site.

Critical Impact
Remote unauthenticated attackers can manipulate the Host header to redirect users to attacker-controlled domains, enabling credential theft and phishing against mirror-registry users.

Affected Products

Red Hat mirror-registry
OpenShift disconnected installation environments using mirror-registry
Downstream deployments consuming affected mirror-registry builds

Discovery Timeline

2025-08-20 - CVE-2025-7777 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-7777

Vulnerability Analysis

The mirror-registry accepts the Host header from client HTTP requests and reuses its value when constructing absolute URLs for redirect responses. Because the header is attacker-controllable, an unauthenticated remote user can inject an arbitrary hostname. The server then issues an HTTP 3xx redirect pointing to that hostname. Victims following a crafted link land on the attacker's infrastructure while the initial request appears to target the legitimate registry.

The root weakness is a missing allow-list check against configured server names. Trusting the Host header for URL generation is a well-documented anti-pattern. Related classes of bugs include host header poisoning of password-reset links and cache poisoning.

Root Cause

The application derives redirect targets and self-referential links from the request Host header without validating it against a configured canonical hostname. There is no comparison to an allow-list, no strict virtual host binding, and no rejection of unexpected values. This maps to CWE-601.

Attack Vector

Exploitation requires only network reachability to the mirror-registry endpoint. No authentication or user interaction with the server is needed to craft the malicious link. The attacker sends a request such as GET /some-path HTTP/1.1 with Host: attacker.example. The server responds with a redirect whose Location header references attacker.example. The attacker then distributes the crafted URL through email, chat, or web content. Users clicking the link are silently redirected to the attacker's domain.

No verified public exploit code is available. See the Red Hat CVE-2025-7777 Advisory and Red Hat Bug Report #2382545 for vendor-confirmed technical details.

Detection Methods for CVE-2025-7777

Indicators of Compromise

HTTP requests to mirror-registry where the Host header does not match the configured canonical hostname or IP.
Outbound HTTP 302 or 301 responses from mirror-registry containing Location headers pointing to external, non-registry domains.
Access logs showing repeated requests from the same source with varying, suspicious Host header values.

Detection Strategies

Parse mirror-registry access logs and alert when the Host header value falls outside a defined allow-list of legitimate FQDNs.
Inspect proxy or load-balancer logs for redirect responses whose Location target does not match the registry's own domain.
Correlate user-reported phishing links with registry access logs to identify abuse patterns.

Monitoring Recommendations

Forward mirror-registry and reverse proxy logs to a centralized logging platform and retain them for incident review.
Alert on any 3xx response where the Location header host differs from the server's configured hostname.
Track anomalous spikes in requests carrying uncommon Host header values, which often indicate probing.

How to Mitigate CVE-2025-7777

Immediate Actions Required

Apply the fixed mirror-registry build referenced in the Red Hat CVE-2025-7777 Advisory as soon as it is available for your channel.
Place mirror-registry behind a reverse proxy that enforces a fixed Host header before requests reach the application.
Audit recent access logs for requests carrying unexpected Host values and investigate any linked user activity.

Patch Information

Red Hat tracks remediation under Bugzilla #2382545. Consult the Red Hat CVE-2025-7777 Advisory for the current fixed version and errata references applicable to your subscription.

Workarounds

Configure the fronting reverse proxy (for example, NGINX or HAProxy) to overwrite the Host header with the canonical registry FQDN before forwarding traffic.
Reject requests at the proxy layer when the incoming Host header does not match an approved allow-list.
Disable or restrict any redirect endpoints in mirror-registry that are not required for normal client operation.

bash

# Example NGINX snippet enforcing a canonical Host header for mirror-registry
server {
    listen 443 ssl;
    server_name registry.example.com;

    if ($host != "registry.example.com") {
        return 400;
    }

    location / {
        proxy_set_header Host registry.example.com;
        proxy_pass https://mirror-registry-backend;
    }
}