Dottie.js is a JavaScript utility library designed to facilitate nested object access and manipulation. Versions 2.0.4 through 2.0.6 contain a prototype pollution vulnerability identified as CVE-2026-27837 (CWE-1321). This vulnerability stems from an incomplete fix for a prior issue (CVE-2023-26132). The original mitigation introduced a guard that only validated the first segment of a dot-separated property path to prevent prototype pollution via the __proto__ property. However, this validation was insufficient because an attacker could bypass it by inserting __proto__ at any position other than the first segment in the path. Both the dottie.set() and dottie.transform() functions are vulnerable, as they allow modification of nested object properties without fully sanitizing the path segments. Exploiting this vulnerability enables an attacker to manipulate the prototype of JavaScript objects, potentially altering application behavior, corrupting data, or causing denial of service. The vulnerability is remotely exploitable over the network with low complexity but requires user interaction, such as supplying crafted input to an application using the affected library. The vulnerability affects all applications that depend on dottie.js versions >=2.0.4 and <2.0.7. The vendor released version 2.0.7 with an updated fix that properly validates all segments of the property path to prevent prototype pollution. No known exploits have been reported in the wild as of the publication date.

The prototype pollution vulnerability in dottie.js can have significant impacts on affected applications and organizations. By manipulating the prototype of JavaScript objects, attackers can alter application logic, bypass security controls, or introduce unexpected behavior leading to data integrity issues. This can result in unauthorized data modification, privilege escalation within the application context, or denial of service through application crashes or resource exhaustion. Since dottie.js is a utility library commonly used in Node.js and frontend JavaScript applications, the scope of impact includes web applications, APIs, and backend services that rely on it for object manipulation. The vulnerability is exploitable remotely and requires user interaction, which may limit automated exploitation but still poses a risk in scenarios where user input is processed without sufficient validation. Organizations using vulnerable versions may face increased risk of targeted attacks, especially if the library is used in security-critical components. Although no known exploits are reported yet, the presence of a partial fix indicates that attackers may develop techniques to exploit this residual flaw. Failure to update to the patched version could lead to compromise of application integrity and availability.

To mitigate the risk posed by CVE-2026-27837, organizations should take the following specific actions: 1) Immediately upgrade all instances of dottie.js to version 2.0.7 or later, which contains the complete fix for the prototype pollution vulnerability. 2) Conduct a thorough dependency audit to identify all projects and components using dottie.js, including transitive dependencies, to ensure comprehensive patching. 3) Implement input validation and sanitization on all user-supplied data that may be passed to dottie.set() or dottie.transform() functions to reduce the risk of malicious path injection. 4) Employ runtime application self-protection (RASP) or monitoring tools to detect anomalous prototype modifications or unexpected behavior indicative of exploitation attempts. 5) Review and harden application logic that depends on nested object manipulation to minimize the impact of potential prototype pollution. 6) Educate development teams about secure coding practices related to prototype pollution and the risks of improper object manipulation. 7) Monitor security advisories and threat intelligence feeds for any emerging exploit techniques targeting this vulnerability. These steps go beyond generic patching by emphasizing comprehensive dependency management, input validation, and proactive detection.