A Single Prompt Is All It Takes: Lenovo Chatbot Vulnerability Exposes Customers and Staff
A serious incident was recently uncovered on Lenovo’s website involving its corporate chatbot, Lena, designed to assist customers. Cybernews researchers revealed that Lena was vulnerable to an XSS-based attack chain, enabling attackers—through nothing more than a crafted prompt—to inject arbitrary code, steal active cookies, and even execute scripts on the machines of customer support staff. The flaw proved so severe that, under certain conditions, an attacker could hijack active support sessions and use them to access restricted corporate systems without ever knowing login credentials.
At the core of the vulnerability was improper handling of both incoming requests and Lena’s generated responses. The chatbot eagerly followed user instructions and was capable of producing replies in HTML format—opening the door for malicious code injection. As demonstrated by the researchers, a carefully engineered prompt of roughly 400 characters contained four critical elements: an innocent query about Lenovo laptops, an instruction to format the response in multiple representations including HTML, the insertion of an HTML snippet with a “blank” image designed to exfiltrate cookies to the attacker’s server upon loading, and a final directive compelling the bot to display the image.
Once Lena generated such a response, the malicious code was stored within the chat history. When either a customer or support agent later opened the dialogue, the browser automatically executed the injected commands, sending session data to an external server. In the next step, when the chat was escalated to a live operator, their workstation also rendered the stored HTML, potentially leaking the agent’s cookies to the attackers. These stolen tokens could then be used to enter the support system as the agent—without requiring login credentials—granting access to active and archived customer conversations.
The potential impact extended well beyond cookie theft. According to Cybernews, the injected code could manipulate the platform’s interface, implant keyloggers, redirect operators to phishing sites, spawn deceptive pop-up messages, or even initiate malware downloads. In the long run, such an attack could serve as an entry point for deeper compromises of Lenovo’s corporate infrastructure, planting backdoors and enabling lateral movement across internal networks.
The root cause lay in the absence of strict data filtering and validation—both for user inputs and for the chatbot’s self-generated content. Unlike traditional web applications, where such vulnerabilities have been gradually mitigated through rigorous input sanitization and Content Security Policy (CSP) enforcement, AI-driven bots remain slow to adopt comparable safeguards. Cybernews stresses that organizations must assume any chatbot-generated data could be hostile and implement layered validation and restriction mechanisms.
Lenovo acknowledged the issue after being notified and quietly patched it before public disclosure. According to published details, researchers reported the vulnerability on July 22, 2025, Lenovo confirmed it on August 6, and by August 18 the flaw had been secured. Although no evidence of real-world exploitation has surfaced, the mere possibility of launching malicious scenarios with a single prompt underscores the magnitude of the risk and highlights the urgent need for AI development to progress in parallel with robust security measures.
As one of the world’s largest technology and services providers—posting revenues of $56.86 billion and net profits of $1.1 billion in the last fiscal year—Lenovo cannot afford weaknesses in its support systems. Incidents like Lena serve as a stark reminder that neglecting security in the deployment of AI tools can create threats as grave as those found in critical enterprise applications.
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