What is the CVSS score of CVE-2026-12900?

CVE-2026-12900 has a CVSS 3.1 base score of 6.4 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.2%.

Spectra Gutenberg Blocks CVE-2026-12900

EUVD-2026-46114 MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2026-07-20 Wordfence

GHSA-3rp7-f8f5-j67m

WordPress XSS Wordpress Plugin Spectra Legacy Gutenberg Blocks Brainstormforce

6.4

CVSS 3.1 · Vendor: Wordfence

Severity by source

Vendor (Wordfence) PRIMARY

6.4 MEDIUM

AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

vuln.today AI

5.4 MEDIUM

PR:L confirmed by Contributor requirement; UI:R because victim must navigate to the injected page for payload execution; S:C reflects cross-browser-context impact.

3.1 AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

4.0 AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

Primary rating from Vendor (Wordfence).

CVSS VectorVendor: Wordfence

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Jul 20, 2026 - 22:16 vuln.today

CVE Published

Jul 20, 2026 - 21:29 cve.org

MEDIUM 6.4

DescriptionCVE.org

The Spectra Gutenberg Blocks - Website Builder for the Block Editor plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the uagb/image block in all versions up to, and including, 2.19.28 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

AnalysisAI

Stored Cross-Site Scripting in the Spectra Legacy - Gutenberg Blocks plugin for WordPress (all versions through 2.19.28) allows low-privileged authenticated attackers to plant persistent malicious scripts via the image block that execute in any visitor's browser. The vulnerability resides in insufficient sanitization and output escaping within the uagb/image block renderer, specifically traced by Wordfence to class-uagb-image.php and block.php. With Contributor-level access - a role available on virtually any multi-author or membership-enabled WordPress site - an attacker can inject payloads that persist until removed, affecting every subsequent visitor. No public exploit code or CISA KEV listing has been identified at time of analysis.

Technical ContextAI

The affected code is the Gutenberg block editor integration for the Spectra (formerly Ultimate Addons for Gutenberg) plugin, developed by Brainstorm Force and identified by CPE cpe:2.3:a:brainstormforce:spectra_legacy_-_gutenberg_blocks:*:*:*:*:*:*:*:*. The uagb/image block registers server-side render callbacks; the vulnerability is in blocks-config/image/class-uagb-image.php at line 59 and includes/blocks/image/block.php at line 10, where block attribute values are echoed into HTML output without adequate escaping. CWE-79 (Improper Neutralization of Input During Web Page Generation) describes the root cause: user-controlled data flows from block attributes stored in the WordPress post meta or block grammar directly into rendered HTML without sanitization via functions such as esc_attr() or wp_kses(). The S:C (scope change) in the CVSS vector correctly reflects that impact is felt in a security context different from the injection point - the attacker writes to the WordPress database, but the payload executes in victims' browsers.

RemediationAI

Update the Spectra Legacy - Gutenberg Blocks plugin to a version beyond 2.19.28 as soon as one is released by Brainstorm Force; monitor the Wordfence advisory at https://www.wordfence.com/threat-intel/vulnerabilities/id/0e9dc5e3-9d72-4c04-8ba9-56428a6fdddd and the WordPress plugin changelog for a confirmed patched release. No exact fixed version was identified in the available data, so 'Upstream fix available; released patched version not independently confirmed' is the current patch status. As a compensating control, restrict Contributor-level user registration and audit existing Contributor accounts for legitimacy, as this eliminates the required access level. Disabling the uagb/image block via a block editor filter (e.g., allowed_block_types_all hook) removes the vulnerable attack surface with the trade-off of losing that block's functionality. Review any existing pages using the image block for injected content using a plugin integrity scanner.