HermeticReader

Vulnerability in Adobe Acrobat Chrome Extension Allowed Theft of WhatsApp Web Conversations

A flaw in the Adobe Acrobat extension for Chrome enabled malicious websites to steal active WhatsApp Web conversations, contacts, and profile information without requiring any user interaction beyond visiting a prepared URL. The vulnerability, tracked as CVE-2026-48294 and named HermeticReader, carried a CVSS score of 7.4 and affected approximately 329 million installations across all versions up to 26.5.2.2. Attackers exploited internal extension pages and missing origin validation to modify local storage, activate the Hermes integration mechanism, and extract rendered chat content by predicting tab identifiers and sending commands to the Acrobat component. The stolen data included contact names, conversation lists, message previews, profile details, and the full text of open chats, all transmitted to attacker servers via hidden forms while leaving end-to-end encryption intact. Adobe addressed the issue in version 26.5.2.3, which was automatically pushed through the Chrome Web Store. No evidence of in-the-wild exploitation had surfaced prior to public disclosure.

Adobe Acrobat Chrome Extension Flaw Enabled Silent Theft of WhatsApp Web Conversations

A vulnerability in the Adobe Acrobat extension for Chrome allowed attackers to silently extract WhatsApp Web conversations, contacts, and account data without any user interaction beyond visiting a malicious page. The issue affected approximately 329 million browser installations and required no password theft or malware infection. Researchers at Guardio named the attack HermeticReader and traced it to an internal messaging flaw that let a hidden iframe execute unverified commands inside the extension. This activated the dormant Hermes integration mechanism, which acted as a bridge to WhatsApp Web and exfiltrated data in plaintext while the user viewed an ordinary webpage. Adobe received the report, fixed the bug in June, and assigned it CVE-2026-48294, classifying it as a UXSS vulnerability that enables cross-site data disclosure. The extension's failure to validate message sources allowed the malicious site to write data to local storage and trigger the integration without warnings.