CVE-2024-1936 in Thunderbird
Summary
by MITRE • 03/05/2024
The encrypted subject of an email message could be incorrectly and permanently assigned to an arbitrary other email message in Thunderbird's local cache. Consequently, when replying to the contaminated email message, the user might accidentally leak the confidential subject to a third party. While this update fixes the bug and avoids future message contamination, it does not automatically repair existing contaminations. Users are advised to use the repair folder functionality, which is available from the context menu of email folders, which will erase incorrect subject assignments. This vulnerability affects Thunderbird < 115.8.1.
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Analysis
by VulDB Data Team • 06/20/2025
The vulnerability described in CVE-2024-1936 represents a critical data integrity issue within Mozilla Thunderbird's local email caching mechanism that could lead to severe confidentiality breaches. This flaw specifically impacts the handling of encrypted email subjects within Thunderbird's local database cache, where the encrypted subject content becomes incorrectly associated with different email messages. The vulnerability arises from improper cache management during the processing of encrypted messages, creating a scenario where legitimate subject information gets permanently misassigned to unrelated email entries in the local storage.
The technical implementation of this vulnerability stems from inadequate validation and assignment procedures within Thunderbird's email caching subsystem, which operates under the broader context of email security protocols and local data management. When Thunderbird processes encrypted messages, it maintains a local cache that stores various message attributes including subject lines for quick access and display purposes. The flaw occurs during the cache update process where encrypted subject data gets incorrectly mapped to the wrong message identifiers, creating a persistent data corruption state that affects message display and reply functionality. This issue particularly impacts encrypted communications where the subject line contains sensitive information that users expect to remain confidential and properly associated with their intended recipients.
The operational impact of CVE-2024-1936 extends beyond simple data display errors to encompass significant security implications for email confidentiality and user trust. When users reply to contaminated messages, the system may automatically populate the reply subject with the incorrectly assigned encrypted content, potentially exposing confidential information to unintended recipients. This represents a direct violation of the principle of least privilege and data integrity, as users may unknowingly transmit sensitive subject information to parties who should not have access to such details. The vulnerability affects all versions prior to Thunderbird 115.8.1 and demonstrates the critical importance of proper cache management in email clients handling encrypted communications.
Organizations and individual users affected by this vulnerability must understand that while the patch addresses the root cause and prevents future occurrences, existing corrupted data remains persistent until manually repaired. The recommended remediation approach involves utilizing Thunderbird's built-in repair folder functionality, which provides a context menu option accessible through email folder interfaces to clear incorrect subject assignments. This repair mechanism operates under the broader framework of email client data integrity management and reflects industry best practices for addressing cache corruption issues. Security professionals should note this vulnerability aligns with CWE-129 and CWE-200 categories related to improper input validation and information exposure, respectively, while also mapping to ATT&CK techniques involving credential dumping and information disclosure through data corruption attacks. The vulnerability underscores the importance of regular security updates and proper cache maintenance procedures in email systems to prevent unauthorized information leakage and maintain user confidence in encrypted communication channels.