CVE-2026-7465: Spectra Gutenberg Blocks RCE Vulnerability

CVE-2026-7465 Overview

The Spectra Gutenberg Blocks – Website Builder for the Block Editor plugin for WordPress contains a remote code execution vulnerability affecting all versions up to and including 2.19.25. Authenticated attackers with Contributor-level access or higher can execute arbitrary PHP code on the server. The flaw enables threat actors to register a fake uagb/-prefixed block type with an attacker-controlled render_callback, then trigger that callback during block rendering. The vulnerability is tracked under [CWE-269: Improper Privilege Management].

Critical Impact

A Contributor-level account can achieve full remote code execution on the underlying WordPress server, compromising site integrity, stored data, and connected systems.

Affected Products

• Spectra Gutenberg Blocks – Website Builder for the Block Editor (Ultimate Addons for Gutenberg)
• All plugin versions through 2.19.25
• WordPress sites permitting Contributor-level user registration

Discovery Timeline

• 2026-05-30 - CVE-2026-7465 published to NVD
• 2026-06-01 - Last updated in NVD database

Technical Details for CVE-2026-7465

Vulnerability Analysis

The vulnerability resides in the block rendering logic of class-uagb-init-blocks.php around lines 330 and 335. The plugin processes block attributes during post rendering and dynamically registers block types based on user-supplied content. An authenticated attacker embeds two crafted blocks in a single post: the first registers a fake block type prefixed with uagb/ and supplies an attacker-controlled render_callback. The second block of the same fake type triggers PHP's call_user_func() against that callback during sequential block rendering in the same page request.

Because render_callback accepts any PHP callable, the attacker chooses arbitrary functions such as system, exec, or assert to execute code. The plugin fails to validate that the callback originates from a trusted source or that the block type was registered by the plugin itself.

Root Cause

The root cause is improper privilege management [CWE-269] combined with missing capability checks on block-type registration during render. Contributor-level users can normally save post content but should not influence server-side execution flow. The plugin treats block attributes embedded in post content as authoritative for dynamic callback registration, collapsing the trust boundary between post content and executable code.

Attack Vector

Exploitation requires network access and authenticated Contributor-level access or higher. The attacker creates or edits a post containing two crafted Gutenberg blocks. When the post is rendered — including draft preview — the plugin registers the fake block type and immediately invokes the attacker-specified callback via call_user_func(). No social engineering or victim interaction beyond standard post rendering is required.

Specific exploitation code is not reproduced here. Technical references are available in the Wordfence Vulnerability Analysis and the WordPress Plugin Code Line 330 source reference.

Detection Methods for CVE-2026-7465

Indicators of Compromise

• Post or page content containing two adjacent Gutenberg blocks with a uagb/-prefixed block name not shipped by the plugin.
• Block attributes including a render_callback field referencing PHP functions such as system, exec, shell_exec, passthru, or assert.
• New or modified PHP files in wp-content/uploads/ or plugin directories shortly after Contributor account activity.
• Outbound network connections from the web server to unfamiliar hosts following post-preview or post-publish events.

Detection Strategies

• Inspect the wp_posts table for post_content containing wp:uagb/ block markers paired with render_callback attribute keys.
• Review web server access logs for POST requests to /wp-admin/post.php or /wp-json/wp/v2/posts from Contributor accounts, followed by preview requests.
• Monitor PHP error logs for warnings referencing call_user_func() invocations against unexpected functions.

Monitoring Recommendations

• Alert on creation or promotion of Contributor-level WordPress accounts on production sites.
• Enable file integrity monitoring on the WordPress webroot and wp-content/plugins/ultimate-addons-for-gutenberg/.
• Capture process telemetry from the PHP-FPM or Apache worker processes to detect child processes such as sh, curl, or wget.

How to Mitigate CVE-2026-7465

Immediate Actions Required

• Update the Spectra Gutenberg Blocks plugin to a version newer than 2.19.25 as soon as a patched release is available from the vendor.
• Audit all Contributor, Author, and Editor accounts and remove any that are unused, untrusted, or were recently created.
• Restrict new user registration where Contributor or higher roles are granted by default.
• Review existing posts and drafts for the two-block exploitation pattern before re-enabling the plugin.

Patch Information

Review the affected code at WordPress Plugin Code Line 330 and WordPress Plugin Code Line 335. Consult the WordPress Plugin Developer Resources page for the latest fixed release. Verify the installed version via the WordPress admin Plugins screen after updating.

Workarounds

• Deactivate the Spectra Gutenberg Blocks plugin until a fixed version is installed.
• Temporarily downgrade Contributor and Author accounts to Subscriber until the patch is applied.
• Deploy a web application firewall rule that blocks post submissions containing render_callback attributes inside uagb/-prefixed block markup.
• Disable post preview for non-Editor roles via a custom capability filter where feasible.

# Configuration example: disable the plugin via WP-CLI until patched
wp plugin deactivate ultimate-addons-for-gutenberg
wp user list --role=contributor --field=ID | xargs -I {} wp user set-role {} subscriber