How to fix CVE-2025-31638?

Within 24 hours: Identify all systems running themeton Spare and assess exposure by checking if the application is internet-facing or accessible to untrusted users. Within 7 days: Implement compensating controls including WAF rules to block XSS payloads, disable user input features where feasible, and restrict access via network segmentation if possible. Within 30 days: Upgrade to themeton Spare version 1.8 or later once available, or conduct a full risk assessment to determine if alternative solutions are needed if no patch is released.

CVE-2025-31638

EUVD-2025-17504 HIGH

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

2025-06-09 [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 14, 2026 - 19:21 vuln.today

EUVD ID Assigned

Mar 14, 2026 - 19:21 euvd

EUVD-2025-17504

CVE Published

Jun 09, 2025 - 16:15 nvd

HIGH 7.1

DescriptionNVD

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in themeton Spare allows Reflected XSS. This issue affects Spare: from n/a through 1.7.

AnalysisAI

Reflected Cross-Site Scripting (XSS) vulnerability in themeton Spare versions up to 1.7 that allows unauthenticated attackers to inject malicious scripts into web pages viewed by users. The vulnerability exists due to improper neutralization of user input during web page generation (CWE-79), enabling attackers to steal session tokens, perform actions on behalf of users, or redirect users to malicious sites. With a CVSS score of 7.1 and network-based attack vector requiring no special privileges, this vulnerability poses a moderate-to-significant risk to any organization deploying Spare.

Technical ContextAI

The vulnerability stems from CWE-79 (Improper Neutralization of Input During Web Page Generation), a fundamental input validation failure where user-supplied data is reflected in HTTP responses without proper HTML/JavaScript encoding or sanitization. In the context of themeton Spare, an application likely used for theme/template management or content delivery, the flaw occurs when user input (via URL parameters, form fields, or HTTP headers) is directly incorporated into dynamically generated HTML responses. The reflected nature (as opposed to stored) means the malicious payload must be delivered through a crafted URL or request, but does not require the payload to be permanently stored in a database. The CVSS vector (AV:N/AC:L/PR:N/UI:R/S:C) indicates the attack is network-accessible with low complexity, requires no authentication, but does require user interaction (clicking a malicious link), and impacts confidentiality, integrity, and availability across scope boundaries.

RemediationAI

Immediate Actions: (1) Upgrade themeton Spare to the latest version (verify if 1.8+ is available and patched; check themeton's official repository/website). (2) If upgrade is not immediately feasible, implement Web Application Firewall (WAF) rules to detect and block reflected XSS payloads (common patterns: script tags, event handlers like onerror, javascript: URIs). (3) Apply Content Security Policy (CSP) headers to restrict script execution to trusted sources only. (4) Long-term: Ensure input validation and output encoding is applied to all user-supplied data before reflection in HTML responses; use parameterized templating engines that auto-escape by default. References to Check: Consult themeton's official GitHub repository (github.com/themeton/spare or similar), official website security advisories, and NVD entry for patch availability links. No vendor advisory URL is provided in the input data; obtain it directly from themeton.

CVE-2025-31638 vulnerability details – vuln.today

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