CVE-2026-77838 in SOY Calendar
Summary
by MITRE • 08/28/2026
SOY Calendar contains a cross-site scripting vulnerability. An arbitrary script may be executed on the web browser of the user who is logging in to the product.
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Analysis
by VulDB Data Team • 08/28/2026
The SOY Calendar application suffers from a Cross-Site Scripting (XSS) vulnerability, which represents a significant security flaw within its input validation and output encoding mechanisms. This type of vulnerability occurs when an application includes untrusted data in a new web page without proper validation or escaping. In the specific context of SOY Calendar, the flaw allows an attacker to inject malicious scripts into pages viewed by other users. The primary vector for this exploitation involves tricking a victim user into logging into the product while interacting with a specially crafted request or link that contains the injected script payload. When the browser renders the compromised page containing the malicious code, it executes the script within the context of the application's domain, effectively bypassing standard security controls like the same-origin policy.
From a technical perspective, this vulnerability likely stems from insufficient sanitization of user-supplied input fields or URL parameters that are reflected back to the client side without adequate encoding. The attacker crafts a malicious payload, typically consisting of JavaScript code embedded within HTML tags such as script elements or event handlers like onerror or onload. When an authenticated user accesses the vulnerable endpoint or page component, the browser interprets this injected content as legitimate executable code belonging to the SOY Calendar application. This execution environment grants the malicious script access to all cookies, session tokens, and other sensitive data associated with that domain, which are typically protected from external scripts by default security policies.
The operational impact of this vulnerability is severe because it compromises the confidentiality and integrity of user sessions within the calendar system. An attacker can steal authentication credentials or session identifiers, allowing them to impersonate legitimate users without needing their passwords. Beyond simple credential theft, the ability to execute arbitrary JavaScript enables more sophisticated attacks such as keylogging, where every keystroke entered by the victim is captured and sent back to the attacker's server. It also facilitates actions like modifying calendar entries, deleting events, or redirecting users to phishing sites that mimic the SOY Calendar login page to harvest additional credentials. Since the script runs with the privileges of an authenticated user, it can perform any action that a legitimate user could perform, effectively giving the attacker full control over the victim's account within the application context.
This vulnerability aligns closely with CWE-79, which is classified as Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. In terms of offensive security frameworks, this exploit maps to MITRE ATT&CK technique T1059, specifically sub-technique 007 for JavaScript execution. The attack lifecycle involves initial access through social engineering or direct exploitation, followed by command and control via data exfiltration using the stolen session tokens or cookies. To mitigate this risk, developers must implement strict input validation on all user-supplied data before processing it server-side. Furthermore, output encoding is critical; any data rendered in HTML should be encoded to ensure that special characters are treated as literal text rather than executable code. Utilizing Content Security Policy headers can also help by restricting the sources from which scripts can be loaded and executed, thereby limiting the damage even if an injection attempt succeeds. Regular security testing including dynamic application security scanning is recommended to identify such flaws early in the development lifecycle.