How to fix CVE-2025-49873?

Within 24 hours: Identify all systems running Elessi theme versions through 6.3.9 and assess customer-facing exposure; activate web application firewall (WAF) rules to block reflected XSS patterns in Elessi parameters. Within 7 days: Deploy input validation and output encoding controls; implement Content Security Policy (CSP) headers; conduct security awareness briefing for support teams on XSS attack indicators. Within 30 days: Contact NasaTheme for patch ETA; evaluate alternative theme solutions; perform vulnerability scanning and penetration testing on affected instances.

Is NasaTheme Elessi affected by CVE-2025-49873?

A reflected cross-site scripting (XSS) vulnerability in Elessi theme versions up to 6.3.9 allows attackers to inject malicious scripts that execute in user browsers, potentially compromising customer data, session credentials, and brand trust.

NasaTheme Elessi CVE-2025-49873

EUVD-2025-28328 HIGH

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

2025-06-20 [email protected]

XSS

7.1

CVSS 3.1

CVSS VectorNVD

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

Low

Lifecycle Timeline

Analysis Generated

Mar 15, 2026 - 00:19 vuln.today

EUVD ID Assigned

Mar 15, 2026 - 00:19 euvd

EUVD-2025-28328

CVE Published

Jun 20, 2025 - 15:15 nvd

HIGH 7.1

DescriptionNVD

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in NasaTheme Elessi allows Reflected XSS. This issue affects Elessi: from n/a through 6.3.9.

AnalysisAI

CVE-2025-49873 is a Reflected Cross-Site Scripting (XSS) vulnerability in NasaTheme's Elessi WordPress theme that allows unauthenticated attackers to inject malicious scripts into web pages viewed by victims. Versions up to and including 6.3.9 are affected. An attacker can steal session cookies, perform actions on behalf of users, or redirect users to malicious sites with minimal complexity (network-accessible input, user interaction required). The vulnerability lacks confirmed EPSS data and KEV listing at this time, but the CVSS 7.1 score and reflected XSS nature indicate moderate-to-high priority.

Technical ContextAI

This vulnerability exploits improper input sanitization in the Elessi WordPress theme during web page generation (CWE-79: Improper Neutralization of Input During Web Page Generation). The Elessi theme, developed by NasaTheme, is a commercial WordPress theme commonly used for e-commerce and business websites. The vulnerability is a Reflected XSS, meaning malicious input is echoed back in the HTTP response without proper HTML entity encoding or Content Security Policy protections. Affected CPE would be: cpe:2.3:a:nasatheme:elessi:*:*:*:*:*:wordpress:*:* (versions ≤6.3.9). Root cause is failure to sanitize user-supplied input parameters before rendering them in HTML context, typically in template files or shortcodes that process query parameters, POST data, or custom fields without wp_kses_post() or esc_html() WordPress escaping functions.

RemediationAI

Immediate patch: Update Elessi theme to version 6.4.0 or later (version number inferred as first patched release; verify on NasaTheme official site or WordPress.org). 2. If patch unavailable: Temporarily disable or replace Elessi theme with alternative theme until patch is released. 3. Input validation workaround: If theme modification is necessary, audit affected template files for user input handling and apply WordPress escaping functions (esc_html(), esc_attr(), wp_kses_post()) to all echo statements. 4. WAF mitigation: Deploy Web Application Firewall rules to block common XSS payloads (e.g., <script>, javascript:, onerror=) in query parameters and POST data. 5. Content Security Policy (CSP): Implement strict CSP headers (Content-Security-Policy: default-src 'self'; script-src 'self') to mitigate XSS impact even if injected. 6. Monitor: Check theme update notifications in WordPress Dashboard; follow NasaTheme security advisories. 7. Validation: After patching, test with XSS payloads (e.g., <img src=x onerror=alert(1)>) in suspected input parameters to confirm fix.

CVE-2025-49873 vulnerability details – vuln.today

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