CVE-2025-39523: GoodBarber Open Redirect Vulnerability

CVE-2025-39523 Overview

CVE-2025-39523 is an open redirect vulnerability affecting the GoodBarber WordPress plugin. The flaw exists in versions up to and including 1.0.26 and is categorized under [CWE-601] (URL Redirection to Untrusted Site). Attackers can craft URLs that appear to originate from a trusted GoodBarber-powered site but redirect victims to attacker-controlled destinations after user interaction.

Critical Impact
Attackers can leverage the trusted domain to launch phishing campaigns, distribute malware, or harvest credentials by redirecting users to malicious sites.

Affected Products

GoodBarber WordPress plugin versions through 1.0.26
WordPress installations running the vulnerable plugin
Sites relying on GoodBarber for mobile app integration

Discovery Timeline

2025-09-09 - CVE-2025-39523 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-39523

Vulnerability Analysis

The GoodBarber plugin fails to validate user-supplied URLs before performing redirection. This allows an attacker to append a crafted redirect parameter to a legitimate GoodBarber endpoint. When a victim clicks the manipulated URL, the site processes the redirection and forwards the browser to an untrusted external destination.

The issue falls under [CWE-601], which covers URL redirection to untrusted sites. The vulnerability requires user interaction, meaning a victim must click a crafted link. Because the initial request targets the trusted GoodBarber domain, security-aware users and email filtering systems may treat the URL as legitimate.

The EPSS probability score sits at 0.245%, reflecting a low current likelihood of active exploitation attempts. However, open redirects remain a common building block in phishing kits and multi-stage attack chains.

Root Cause

The root cause is missing or insufficient validation of redirect target URLs within the GoodBarber plugin. The plugin accepts a destination parameter without verifying that the target belongs to an allowlist of trusted domains. This design flaw permits arbitrary external URLs to be passed to the redirect handler.

Attack Vector

An attacker crafts a URL pointing to a vulnerable GoodBarber endpoint on a legitimate WordPress site. The URL includes a redirect parameter referencing an attacker-controlled domain. The attacker delivers the link through email, social media, or messaging platforms. Once the victim clicks the link, the browser is redirected to the malicious destination, which may host a credential harvesting page or drive-by download payload.

The vulnerability requires no authentication and can be exploited over the network. Refer to the Patchstack Vulnerability Report for technical details on the affected parameter.

Detection Methods for CVE-2025-39523

Indicators of Compromise

Web server access logs containing GoodBarber plugin URLs with suspicious redirect parameters pointing to external domains
HTTP referer headers on external sites originating from GoodBarber redirect endpoints
User reports of unexpected redirection from trusted WordPress sites to unfamiliar domains

Detection Strategies

Inspect WordPress access logs for GoodBarber plugin requests that include URL parameters containing full URLs or protocol-relative paths
Deploy web application firewall (WAF) rules that flag redirect parameters referencing external domains
Correlate outbound HTTP 302 responses from GoodBarber endpoints with the destination domain to identify redirects to non-trusted hosts

Monitoring Recommendations

Enable verbose logging on the WordPress installation and forward logs to a centralized SIEM for query and correlation
Monitor phishing intelligence feeds for domains impersonating sites that run the GoodBarber plugin
Track user-reported phishing incidents that reference legitimate GoodBarber-powered domains as the initial redirect origin

How to Mitigate CVE-2025-39523

Immediate Actions Required

Identify all WordPress instances running the GoodBarber plugin at version 1.0.26 or earlier
Update the GoodBarber plugin to the latest patched version released by the vendor
Review web server access logs for prior exploitation attempts targeting the redirect endpoint

Patch Information

The vendor has published mitigation guidance through Patchstack. Site administrators should upgrade the GoodBarber plugin to a version above 1.0.26. Consult the Patchstack Vulnerability Report for the current fixed version and remediation details.

Workarounds

Configure a WAF rule to block requests to GoodBarber endpoints when the redirect parameter contains external URLs or protocol schemes
Temporarily disable the GoodBarber plugin on affected WordPress installations until the patch is applied
Implement a domain allowlist at the reverse proxy layer to restrict permissible redirect destinations

bash

# Example WAF rule (ModSecurity) to block external redirects via GoodBarber
SecRule REQUEST_URI "@contains /goodbarber/" \
  "chain,deny,status:403,id:1039523,msg:'Blocked potential open redirect - CVE-2025-39523'"
  SecRule ARGS "@rx ^https?://(?!yourdomain\.com)" \
    "t:none,t:urlDecode"