CVE-2026-111714 in tarteaucitron.js
Summary
by MITRE • 10/16/2026
tarteaucitron.js before 1.37.0 contains a regular expression denial of service vulnerability that allows attackers to block visitor pages by supplying unescaped cookie names to cookie.purge. Attackers can plant a cookie from a sibling subdomain or inject a purgeBtn element with a catastrophic-backtracking data-cookie pattern that freezes the page when the purge button is clicked.
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Analysis
by VulDB Data Team • 10/16/2026
The vulnerability identified in tarteaucitron.js prior to version 1.37.0 represents a significant regular expression denial of service, commonly referred to as ReDoS. This flaw resides within the library's cookie management logic, specifically affecting the purge functionality which is responsible for removing user consent cookies. The core technical issue stems from an inadequately constructed regular expression used in the cookie.purge method. When this function processes input data without proper sanitization or complexity limits, it becomes susceptible to catastrophic backtracking. This occurs when a regex engine attempts multiple ways to match a string that ultimately fails to meet all criteria of the pattern, causing exponential growth in processing time relative to the length and structure of the input string rather than linear scaling.
Attackers can exploit this vulnerability through two primary vectors depending on their access level within the web application's domain hierarchy. In scenarios where an attacker has control over a sibling subdomain or can inject scripts into the page context, they may plant a specifically crafted cookie with an unescaped name designed to trigger the regex engine's worst-case performance characteristics. Alternatively, if the attacker possesses the ability to manipulate the DOM by injecting a purgeBtn element, they can directly supply a data-cookie attribute containing a catastrophic-backtracking pattern. When a user interacts with this injected button or when the library attempts to process the malicious cookie during standard operation, the browser’s JavaScript engine becomes locked in an infinite loop of backtracking computations. This effectively freezes the page, rendering it unresponsive and blocking any further interaction for legitimate visitors.
The operational impact of this vulnerability is severe from a user experience perspective and potentially affects availability metrics. By freezing the client-side execution thread, the attacker creates a denial-of-service condition that targets individual users rather than server infrastructure. Since JavaScript runs on the main UI thread in most browsers, a long-running regex operation blocks event handling, rendering clicks, scrolls, and other inputs ineffective until the garbage collector or browser timeout intervenes. This can lead to increased bounce rates, loss of user trust, and potential degradation of service availability for applications relying heavily on this library for consent management compliance with regulations such as GDPR or CCPA.
From a classification standpoint, this vulnerability aligns with CWE-400, which covers Uncontrolled Resource Consumption, specifically manifesting as ReDoS. It also relates to CWE-730, which addresses injection of harmful data that leads to unexpected behavior in security-critical functions like cookie handling. In the context of the MITRE ATT&CK framework for web applications, this exploitation technique falls under T1562.004, specifically Impair Defenses via Obfuscated or Unusual Encoding, although more accurately it maps to resource exhaustion tactics that hinder service availability. The attack vector is generally classified as Local if exploiting through sibling subdomains due to same-origin policy constraints, but could be Remote if the injection point allows cross-site scripting-like conditions where an attacker can force a victim’s browser to execute the malicious payload.
Mitigation strategies must focus on both immediate patching and long-term defensive coding practices. The primary remediation is upgrading tarteaucitron.js to version 1.37.0 or later, where the regular expression has been optimized to prevent catastrophic backtracking by ensuring linear time complexity for all valid inputs. For environments unable to upgrade immediately, input validation should be implemented on any data passed to cookie-related functions, strictly limiting the length and character set of cookie names. Additionally, developers should avoid using complex regex patterns in performance-critical paths such as event handlers or initialization routines. Implementing a timeout mechanism for long-running JavaScript operations can also mitigate the impact by terminating hung threads before they completely freeze the user interface. Regular security audits focusing on third-party library dependencies are essential to identify similar vulnerabilities in other components that handle untrusted input from subdomains or DOM manipulation points.