CVE-2026-105456 in RT for Incident Response
Summary
by MITRE • 10/30/2026
RTIR extends RT's HTML scrubber to allow an internal link placeholder, and the extension lets through any link that merely contains the placeholder, including links using the executable javascript: scheme. The change applies to the whole RT instance once RTIR is installed, not only to RTIR's own queues. Anyone who can add HTML content to a ticket on such an instance can store such a link. That includes an unauthenticated sender of HTML email to the Incident Reports queue, which RTIR opens to everyone by default. Script runs when a user clicks the link, in that user's session, and can act in RT with that user's authority.
This issue was fixed in version 5.0.11 and 6.0.4
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Analysis
by VulDB Data Team • 10/30/2026
The vulnerability described constitutes a Cross-Site Scripting (XSS) flaw within the Request Tracker (RT) incident response system, specifically introduced by an extension known as RTIR. The core technical failure lies in the HTML scrubbing mechanism that is intended to sanitize user-supplied content before it is rendered in web browsers. While RTIR extends this scrubber to support internal link placeholders for legitimate functionality, the implementation fails to adequately validate the protocol scheme of hyperlinks containing these placeholders. Consequently, any hyperlink utilizing an executable JavaScript URI scheme, such as javascript:, is permitted through the filter if it contains the required placeholder string. This oversight effectively bypasses standard security controls designed to prevent the execution of malicious client-side scripts within the application context.
The operational impact of this vulnerability is significant because it allows for stored XSS attacks that persist in the database and are executed whenever a victim views the affected ticket content. An attacker can inject a crafted HTML link into a ticket, which remains dormant until another user interacts with it by clicking the link. Upon activation, the malicious JavaScript executes within the security context of the currently logged-in user's session. This enables the attacker to perform actions on behalf of that user, such as modifying tickets, accessing sensitive incident data, or escalating privileges, depending on the victim's role and permissions within RTIR. The severity is further compounded by the default configuration of RTIR, which opens the Incident Reports queue to unauthenticated users for email submission. This means an attacker does not even need valid credentials to inject the malicious payload; they can simply send a crafted HTML email to the designated address, ensuring that any authenticated administrator or analyst who views the ticket becomes a victim.
From a classification perspective, this vulnerability aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation (Cross-site Scripting). The specific mechanism involves insufficient validation of URI schemes, relating closely to CWE-829 and CWE-106 in the context of input handling. In terms of adversary behavior, this flaw facilitates actions consistent with MITRE ATT&CK technique T1059, specifically Command and Scripting Interpretation via JavaScript, as well as T1078 for Valid Accounts if the victim is authenticated. The attack vector leverages social engineering through email to deliver the payload, which corresponds to T1566 Phishing.
Mitigation strategies must address both the immediate technical flaw and broader configuration security. Organizations running RTIR versions prior to 5.0.11 or 6.0.4 are advised to upgrade immediately to these patched releases where the HTML scrubber logic has been corrected to reject executable schemes even when placeholders are present. For environments that cannot patch immediately, a temporary workaround involves restricting access to the Incident Reports queue so that it is not open to unauthenticated email submissions. Additionally, implementing strict Content Security Policy (CSP) headers can help mitigate the impact of any remaining XSS vectors by preventing the execution of inline scripts or unauthorized external script sources. Regular auditing of HTML sanitization rules and ensuring that extensions do not introduce bypasses in security filters are critical practices for maintaining the integrity of web-based ticketing systems.