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CSS & JavaScript Toolbox CVE-2025-13533

| EUVDEUVD-2025-210931 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-09-18 Wordfence GHSA-6jx6-9xqq-pg98
4.4
CVSS 3.1 · Vendor: Wordfence
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain Administrator access to wp-admin
  2. Delivery
    Inject script into Assignment Engine field
  3. Exploit
    Payload stored in plugin block data
  4. Execution
    Admin opens CJT block edit screen
  5. Impact
    Script executes in dashboard browser context

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Requires an authenticated WordPress user with Administrator-level access or above to store the payload in the CSS & JavaScript Toolbox 'Assignment Engine' fields - specifically Expressions, URLs, or Advanced assignment data. Execution is further gated on a user (in practice another admin-area user) subsequently opening the CJT block edit screen in the wp-admin dashboard. Limiting factors: highest-privilege injection prerequisite (PR:H), admin-only victim surface, and the fact that an Administrator can already legitimately inject scripts through this plugin's intended functionality, sharply reducing added impact. Affects all versions up to and including 12.0.6.

Impact

This is a low-priority issue despite the CWE-79 stored XSS classification. The vendor CVSS of 4.4 (AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N) is driven down by PR:H, which the description substantiates: exploitation requires Administrator-level access or above to write the malicious payload into the Assignment Engine fields (Expressions, URLs, Advanced assignment data). No EPSS score, no CISA KEV listing, and no public exploit code were provided - so this is 'no public exploit identified at time of analysis.' The payload only fires when a user opens the CJT block edit screen inside the wp-admin dashboard, meaning both the injector and the victim are privileged admin-area users; this is effectively an admin-on-admin (near-self-XSS) condition with little privilege gain, since an Administrator can already inject arbitrary JS/CSS via this plugin's core function. The vendor's UI:N is questionable - the description explicitly conditions execution on a user navigating to the block edit screen, which is user interaction; I assess UI:R. The S:C (scope change) is defensible for browser-context XSS crossing the plugin's security authority. Net: real but low real-world risk, gated behind the highest privilege tier.

Exploit ScenarioDerived

An attacker who has already obtained WordPress Administrator access (e.g., via a compromised admin account or a second-stage foothold) injects a malicious script into an Assignment Engine field such as an Expression or URL. The stored payload then executes in the browser of any admin who later opens the CJT block edit screen, enabling session/cookie theft or admin-dashboard actions. No public POC was provided in the input.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 18, 2026

Stored cross-site scripting in the WordPress plugin CSS & JavaScript Toolbox (all versions up to and including 12.0.6) lets an authenticated user with Administrator-level access persist arbitrary JavaScript through the plugin's Assignment Engine fields - Expressions, URLs, and Advanced assignment data - which is later executed when an administrator opens the CJT block edit screen in wp-admin. Because the injection prerequisite is already Administrator-level access, and an Administrator can legitimately place script and CSS content through this plugin's intended functionality, the marginal impact is small, making this a low-priority issue despite the stored XSS classification. No public exploit code has been identified at time of analysis, and the flaw maps to CWE-79 (improper neutralization of input during web page generation).

RemediationAI

Patch status: upstream fix available (repository commit/changeset, e.g. https://plugins.trac.wordpress.org/changeset?reponame=&old=3667323%40css-javascript-toolbox&new=3667323%40css-javascript-toolbox); a released, tagged patched version is not independently confirmed in the provided data, so administrators should update to the first CSS & JavaScript Toolbox release published after 12.0.6 and verify the installed version no longer matches the affected range. If the plugin is not actively needed, deactivating and deleting it removes the attack surface entirely and is the lowest-risk option where CJT functionality is not in use. Where a patched release is not yet deployable and the plugin must stay enabled, compensating controls should target the Administrator prerequisite that the assessment identifies as the main limiting factor: enforce least privilege by keeping the number of Administrator accounts to the minimum required, audit and remove dormant or shared admin accounts, and enable two-factor authentication for all administrators - recognizing that these reduce the pool of potential injectors but do not stop a determined administrator. Administrators can also review the Assignment Engine entries (Expressions, URLs, and Advanced assignment data) of any existing CJT blocks for unexpected script content and clear suspicious entries, though this is a detection/mitigation measure and not a boundary control, and it will not prevent future injection by an admin-level user. Restricting wp-admin access by IP or a reverse proxy adds further friction for external attackers but introduces operational overhead for legitimate administrators.

Affected VersionsENISA

CSS & JavaScript Toolbox 0 ≤12.0.6

Affected Packages

euvd css_javascript_toolbox no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability is a classic CWE-79 stored cross-site scripting flaw in a WordPress plugin that exists to manage CSS and JavaScript blocks for a site. The Assignment Engine within CSS & JavaScript Toolbox accepts structured configuration data - Expressions, URLs, and an 'Advanced' assignment payload - and stores it without sufficient input sanitization, then renders it without adequate output escaping when the block edit screen is displayed. The block-ajax.php controller (the referenced line 184 in both trunk and the 12.0.6 tag) is the code path implicated, meaning the assignment data flows through an AJAX handler into persistent storage and back out into the admin dashboard UI. Because the sink is the wp-admin CJT block edit screen rather than the public-facing front end, execution is confined to authenticated administrator sessions viewing that screen. The affected package is identified by CPE cpe:2.3:a:wipeoutmedia:css_&_javascript_toolbox, covering every release through 12.0.6; a repository changeset (3667323) indicates the underlying sanitization/escaping was subsequently modified in the plugin's source.

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Severity by source

Vendor (Wordfence) PRIMARY 4.4 MEDIUM
AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N
vuln.today AI 4.8 MEDIUM

Administrator injection makes PR:H; execution needs a victim to open the block edit screen so UI:R; storing a payload is straightforward so AC:L; browser-context XSS gives C:L/I:L and S:C.

3.1 AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

Primary rating from Vendor (Wordfence).

CVSS VectorVendor: Wordfence

Attack Vector
Network
Attack Complexity
High
Privileges Required
High
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

DescriptionCVE.org

The CSS & JavaScript Toolbox plugin for WordPress is vulnerable to Stored Cross-Site Scripting in all versions up to, and including, 12.0.6 via the Assignment Engine fields. This is due to insufficient input sanitization and output escaping on assignment data fields including Expressions, URLs, and Advanced assignment data. This makes it possible for authenticated attackers, with Administrator-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses the CJT block edit screen in the admin dashboard.

Threat Intelligence Overview

EPSS Score
0.2%
Top 90% exploitable
Prevalence
Low
niche WordPress CSS/JS injection plugin, modest installation base
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment GitHub VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

22
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +22
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

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