CVE-2026-6089 Overview
CVE-2026-6089 is a Server-Side Request Forgery (SSRF) vulnerability affecting the WP CTA plugin for WordPress in all versions up to and including 2.1.2. The flaw resides in the import_sidebars() function, which processes the sticky_s_media parameter from imported JSON files. The function passes user-supplied URLs to PHP's file_get_contents() after applying only FILTER_VALIDATE_URL validation, which does not block internal IP addresses. Authenticated attackers with Administrator-level access can force the WordPress server to issue arbitrary HTTP requests, and the response body is stored as a WordPress media attachment, producing a full-read SSRF condition [CWE-918].
Critical Impact
Administrator-authenticated attackers can query internal services and exfiltrate response content via WordPress media attachments, exposing cloud metadata endpoints and internal APIs otherwise unreachable from the internet.
Affected Products
- WP CTA plugin (easy-sticky-sidebar) for WordPress — all versions through 2.1.2
- WordPress sites running the vulnerable plugin with Administrator accounts exposed to untrusted actors
- Multi-tenant WordPress hosting environments where Administrator roles are delegated
Discovery Timeline
- 2026-07-29 - CVE-2026-6089 published to the National Vulnerability Database
- 2026-07-30 - Last updated in NVD database
Technical Details for CVE-2026-6089
Vulnerability Analysis
The vulnerability exists in the plugin's JSON import workflow. When an administrator imports sidebar configuration data, the import_sidebars() function reads the sticky_s_media field from the JSON payload and treats it as a URL for remote media retrieval. The plugin validates the value using PHP's FILTER_VALIDATE_URL filter and then invokes file_get_contents() directly against the supplied string.
FILTER_VALIDATE_URL only confirms syntactic URL validity. It does not restrict scheme, host, or destination IP ranges. As a result, URLs pointing to RFC 1918 private ranges, loopback interfaces, link-local addresses such as 169.254.169.254, or cloud provider metadata services pass validation. The retrieved response body is written to the WordPress media library, allowing the attacker to retrieve and read the full response.
Root Cause
The root cause is insufficient URL validation before performing an outbound HTTP request. The plugin trusts syntactic validation as a security boundary and omits an allow-list of permitted hosts, a denial list of private ranges, or a scheme restriction limiting the request to http/https on public endpoints. See the WordPress Plugin Code Reference for the affected code path.
Attack Vector
An attacker with Administrator privileges uploads or imports a crafted JSON configuration file containing a sticky_s_media value pointing at an internal resource, for example a cloud metadata endpoint, an internal admin panel, or a service bound to 127.0.0.1. The plugin fetches the URL server-side and stores the response as a media attachment. The attacker then downloads the attachment to read the response body. Full technical details are available in the Wordfence Vulnerability Analysis.
Detection Methods for CVE-2026-6089
Indicators of Compromise
- New media attachments in wp-content/uploads/ whose contents are JSON, HTML, or plaintext rather than image binaries
- WordPress import_sidebars() execution correlated with outbound requests to 127.0.0.1, 169.254.169.254, or RFC 1918 addresses
- Unexpected entries in the wp_posts table with post_type = 'attachment' created shortly after a plugin import action
Detection Strategies
- Inspect web server and PHP-FPM logs for requests to admin.php or admin-ajax.php invoking the WP CTA import handler followed by outbound connections to internal ranges
- Alert on file_get_contents() calls originating from the easy-sticky-sidebar plugin path in application-layer telemetry
- Review recent media library uploads with MIME types inconsistent with their file extensions
Monitoring Recommendations
- Log all outbound HTTP requests from PHP worker processes and flag connections to loopback, link-local, and private address ranges
- Monitor WordPress admin activity for JSON import operations against the WP CTA plugin
- Track creation of Administrator-level accounts and privilege changes that could enable exploitation
How to Mitigate CVE-2026-6089
Immediate Actions Required
- Update the WP CTA (easy-sticky-sidebar) plugin to the version published in changeset 3491924 or later
- Audit Administrator accounts and remove any that are unused or unnecessary
- Review recent media attachments for evidence of SSRF response capture
Patch Information
The vendor addressed the issue in the release following version 2.1.2, tracked in the plugin's SVN changeset 3491924. The fix adds validation to reject URLs pointing at internal address ranges before invoking file_get_contents(). Administrators should apply the update through the WordPress plugin management interface.
Workarounds
- Deactivate and remove the WP CTA plugin until patched versions can be deployed
- Restrict Administrator role assignment to trusted, MFA-protected accounts only
- Enforce egress filtering at the network layer to block PHP worker processes from reaching cloud metadata endpoints and internal management interfaces
- Deploy a web application firewall rule inspecting JSON import payloads for URLs targeting private IP ranges
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
