CVE-2010-0163 in Thunderbird
Summary
by MITRE
Mozilla Thunderbird before 2.0.0.24 and SeaMonkey before 1.1.19 process e-mail attachments with a parser that performs casts and line termination incorrectly, which allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted message, related to message indexing.
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Analysis
by VulDB Data Team • 05/03/2026
The vulnerability identified as CVE-2010-0163 represents a critical security flaw affecting Mozilla Thunderbird versions prior to 2.0.0.24 and SeaMonkey versions prior to 1.1.19. This vulnerability stems from improper handling of email attachments within the message parsing mechanism, specifically involving incorrect casting operations and flawed line termination processing. The flaw exists in the core message indexing functionality that processes incoming email content, making it particularly dangerous as it can be triggered by simply receiving an email message. The issue manifests when the email parser encounters specially crafted attachments that exploit memory management inconsistencies in the application's handling of data types and string processing operations.
The technical exploitation of this vulnerability occurs through a carefully constructed email message containing malformed attachments that trigger incorrect type casting and improper line termination handling within the mail client's parsing engine. When Thunderbird or SeaMonkey attempts to index and process such a message, the flawed parser performs invalid memory operations that can lead to application instability and potential code execution. The vulnerability falls under the category of buffer overflows and memory corruption issues, specifically aligning with CWE-121 for heap-based buffer overflow conditions and CWE-125 for out-of-bounds read errors. Attackers can leverage this flaw to either crash the application through denial of service or potentially execute arbitrary code if they can control the memory layout and overwrite critical program structures.
From an operational perspective, this vulnerability poses significant risk to email security and system availability within enterprise environments where these older versions of email clients are still deployed. The attack vector requires only that a user receives a malicious email message, making it particularly dangerous for targeted attacks against organizations. The impact extends beyond simple application crashes to potentially allowing remote code execution, which could enable attackers to establish persistent access to compromised systems. This vulnerability directly relates to ATT&CK technique T1190 for Exploit Public-Facing Application and T1059 for Command and Scripting Interpreter, as it can be used to gain initial access and establish command execution capabilities. The vulnerability's exploitation is particularly concerning because it affects widely used email clients that are often deployed in corporate environments with limited patch management processes.
Mitigation strategies for CVE-2010-0163 should prioritize immediate patch deployment for all affected versions of Thunderbird and SeaMonkey, with particular attention to legacy systems that may not receive regular updates. Organizations should implement email filtering solutions that can identify and quarantine suspicious attachments before they reach end users, focusing on known malicious patterns and file types that commonly exploit this class of vulnerability. Network administrators should consider implementing sandboxing mechanisms for email processing and establishing strict email content filtering policies that block potentially dangerous file types. Additionally, user education regarding the risks of opening unexpected email attachments remains crucial, though this approach is less effective against targeted attacks. The vulnerability highlights the importance of regular security updates and proper patch management protocols, as the flaw existed in widely deployed software for an extended period before resolution. Security teams should also monitor for indicators of compromise related to this vulnerability and ensure that email security solutions are properly configured to detect and prevent exploitation attempts.