CVE-2026-5109 Overview
CVE-2026-5109 is a stored Cross-Site Scripting (XSS) vulnerability in the Gravity Forms plugin for WordPress, affecting all versions up to and including 2.10.0. The flaw resides in the Product Option field, where the state validation function relies on wp_kses()-sanitized values for comparison but persists the raw, unsanitized input to the database. When an administrator opens the entry details page, the option_label is rendered without output escaping in view-order-summary.php at line 32, executing any injected JavaScript. Unauthenticated attackers can submit forms that trigger script execution in an administrator's browser session [CWE-79].
Critical Impact
Unauthenticated attackers can inject JavaScript that executes in administrator browsers, enabling session theft, account takeover, and arbitrary actions in the WordPress admin context.
Affected Products
- Gravity Forms plugin for WordPress, versions up to and including 2.10.0
- WordPress sites with the Product Option field exposed in public forms
- Administrator workflows that render entries via the Order Summary view
Discovery Timeline
- 2026-05-02 - CVE-2026-5109 published to NVD
- 2026-05-05 - Last updated in NVD database
Technical Details for CVE-2026-5109
Vulnerability Analysis
The vulnerability stems from a validation and storage mismatch in how Gravity Forms processes Product Option field submissions. The state validation routine sanitizes the submitted value using wp_kses() and compares the sanitized result against the legitimate option value defined by the form author. If the comparison succeeds, the code accepts the submission as valid. The plugin then writes the original, unsanitized payload into the entries table rather than the sanitized version used for comparison.
When an administrator later opens the entry, view-order-summary.php echoes the stored option_label without applying esc_html() or equivalent escaping. Any HTML or <script> content stored in that field renders directly in the admin DOM. Because submission requires no authentication, anonymous attackers can plant payloads at scale.
Root Cause
The root cause is improper neutralization of input during web page generation, classified as [CWE-79]. Two failures combine: validation operates on a sanitized copy while storage uses the raw value, and the rendering path lacks contextual output escaping. Either control alone would have prevented exploitation.
Attack Vector
An unauthenticated attacker locates a public Gravity Forms form that includes a Product Option field. The attacker manipulates the submitted option value to embed JavaScript while ensuring the wp_kses()-sanitized version still matches a legitimate option label. The malicious entry is stored. When any administrator reviews the entry's Order Summary, the script executes with the administrator's privileges, allowing cookie theft, CSRF actions, or persistent backdoor installation through plugin or theme editing.
No verified proof-of-concept code is publicly available. See the Wordfence Security Vulnerability advisory for additional technical context.
Detection Methods for CVE-2026-5109
Indicators of Compromise
- Gravity Forms entries containing HTML tags, <script> elements, or javascript: URIs in Product Option fields.
- Unexpected administrator account creation, role changes, or plugin/theme file modifications shortly after entry submissions.
- Outbound requests from administrator browsers to unfamiliar domains while viewing the Forms entries page.
Detection Strategies
- Query the wp_gf_entry_meta and related Gravity Forms tables for meta_value entries containing <, >, onerror=, or script substrings.
- Inspect web server access logs for POST requests to form submission endpoints with payloads containing encoded HTML or JavaScript.
- Review WordPress audit logs for administrative actions originating from the Gravity Forms entry view URL pattern admin.php?page=gf_entries.
Monitoring Recommendations
- Enable a Web Application Firewall rule set that flags HTML or script content in form submissions targeting Gravity Forms endpoints.
- Forward WordPress and web server logs to a centralized SIEM such as Singularity Data Lake for correlation between submission events and subsequent admin activity.
- Use endpoint telemetry from Singularity Endpoint on administrator workstations to detect browser-driven actions that follow a stored XSS trigger.
How to Mitigate CVE-2026-5109
Immediate Actions Required
- Update the Gravity Forms plugin to a version above 2.10.0 that addresses the validation and escaping flaw.
- Audit existing entries for malicious payloads in Product Option fields and purge or sanitize affected records before viewing them.
- Rotate WordPress administrator passwords and invalidate active sessions if entry pages were accessed during the exposure window.
Patch Information
Gravity Forms has released a fix tracked in the Gravity Forms Change Log. Apply the latest plugin release through the WordPress dashboard or via WP-CLI. Confirm the installed version exceeds 2.10.0 after the update completes.
Workarounds
- Temporarily disable forms that expose the Product Option field to unauthenticated users until the patch is applied.
- Restrict access to the WordPress admin area with IP allowlisting or VPN-only access to limit who can trigger the rendering of malicious entries.
- Deploy a Content Security Policy (CSP) that disallows inline scripts on wp-admin pages to reduce the impact of stored payloads.
# Update Gravity Forms via WP-CLI on the affected host
wp plugin update gravityforms --version=latest
wp plugin status gravityforms
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
