CVE-2026-59516 in ICS Calendar Plugin
Summary
by MITRE • 07/13/2026
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Room 34 Creative Services, LLC ICS Calendar ics-calendar allows Reflected XSS.This issue affects ICS Calendar: from n/a through <= 12.1.1.
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Analysis
by VulDB Data Team • 07/13/2026
This cross-site scripting vulnerability resides within the ICS Calendar plugin developed by Room 34 Creative Services, LLC, specifically impacting versions ranging from the initial release through version 12.1.1. The flaw manifests as an improper neutralization of input during web page generation, creating a classic reflected XSS attack vector that allows malicious actors to inject client-side scripts into web pages viewed by other users. The vulnerability occurs when user-supplied input is not adequately sanitized or escaped before being rendered in the web interface, enabling attackers to execute arbitrary JavaScript code within the victim's browser context.
The technical implementation of this vulnerability stems from the plugin's failure to properly validate and escape user input parameters that are subsequently reflected back to users in the generated web pages. When an attacker crafts a malicious URL containing crafted script payloads and convinces a victim to click on it, the malicious code executes within the victim's browser session, potentially stealing cookies, session tokens, or performing unauthorized actions on behalf of the user. This type of vulnerability is categorized under CWE-79 as Improper Neutralization of Input During Web Page Generation, which represents one of the most prevalent web application security flaws in the OWASP Top Ten.
The operational impact of this reflected XSS vulnerability extends beyond simple script execution, as it can enable attackers to hijack user sessions, steal sensitive information, manipulate data displayed to users, or redirect them to malicious websites. Attackers can exploit this weakness by crafting phishing URLs that appear legitimate but contain malicious payloads designed to exploit the vulnerable input handling mechanism. The attack typically requires social engineering to convince victims to click on malicious links, making it particularly dangerous in environments where users frequently interact with calendar applications and may be less vigilant about URL authenticity.
Mitigation strategies for this vulnerability include implementing comprehensive input validation and output encoding mechanisms throughout the application's data flow. Developers should employ strict sanitization of all user-supplied input before rendering it in web pages, utilizing proper HTML escaping techniques for dynamic content. Additionally, implementing Content Security Policy headers can provide an additional layer of protection against unauthorized script execution. The most effective long-term solution involves upgrading to version 12.1.2 or later, which contains the necessary patches to address this specific reflected XSS vulnerability. Organizations should also conduct regular security assessments and implement automated scanning tools to identify similar input validation weaknesses that could lead to other types of injection attacks including those mapped to ATT&CK technique T1203 for Exploitation for Credential Access.