CVE-2024-10461 in Thunderbird
Summary
by MITRE • 10/29/2024
In multipart/x-mixed-replace responses, `Content-Disposition: attachment` in the response header was not respected and did not force a download, which could allow XSS attacks. This vulnerability affects Firefox < 132, Firefox ESR < 128.4, Thunderbird < 128.4, and Thunderbird < 132.
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Analysis
by VulDB Data Team • 03/02/2025
The vulnerability identified as CVE-2024-10461 represents a critical security flaw in Mozilla Firefox and Thunderbird web browsers that stems from improper handling of multipart/x-mixed-replace HTTP responses. This type of response is commonly used for streaming content such as live video feeds or dynamic web pages where the server sends multiple parts of a document over time. The core issue lies in how these browsers process the Content-Disposition header when it contains the attachment directive, which should theoretically force the browser to download the content rather than display it inline. When this directive is ignored, attackers can exploit the inconsistency to execute cross-site scripting attacks by crafting malicious multipart responses that bypass normal security mechanisms. The vulnerability specifically affects versions of Firefox prior to 132 and Firefox ESR prior to 128.4, along with Thunderbird versions before 128.4 and 132 respectively, indicating a widespread impact across the Mozilla ecosystem.
The technical exploitation of this vulnerability occurs through the manipulation of HTTP response headers in multipart/x-mixed-replace content streams. When a server responds with a multipart/x-mixed-replace content type and includes a Content-Disposition: attachment header, the browser should enforce a download behavior rather than rendering the content inline. However, the flaw allows the browser to ignore this directive and instead render the content directly in the browser window, creating an execution environment where malicious scripts can be injected and executed. This bypasses normal security restrictions that would typically prevent inline content from executing scripts, particularly when the content is intended to be downloaded. The vulnerability aligns with CWE-1004 which addresses insecure default permissions and improper handling of security-sensitive headers, while also mapping to ATT&CK technique T1203 which involves exploiting web browsers through malicious content delivery.
The operational impact of this vulnerability extends beyond simple XSS attacks to potentially enable more sophisticated exploitation scenarios. Attackers can leverage this flaw to deliver malicious content that appears legitimate due to the forced download behavior, but instead executes scripts in the context of the victim's browser session. This creates opportunities for session hijacking, credential theft, and privilege escalation attacks where the malicious content can interact with the victim's browser environment in ways that would normally be prevented by security mechanisms. The vulnerability affects not only web browsing but also email clients like Thunderbird, which means that users could be compromised through email attachments or web content embedded in email messages. Organizations using these vulnerable browsers face significant risk as the attack surface expands to include both web-based and email-based delivery vectors.
Mitigation strategies for this vulnerability require immediate patching of affected browser versions to ensure proper handling of Content-Disposition headers in multipart responses. System administrators should prioritize updating Firefox and Thunderbird installations to versions 132 or later for Firefox and 128.4 or later for Thunderbird, as these releases contain the necessary security fixes. Additionally, network administrators can implement content filtering rules to detect and block multipart/x-mixed-replace responses with suspicious Content-Disposition headers, though this approach may impact legitimate functionality. Organizations should also consider implementing additional security measures such as strict content security policies and sandboxing mechanisms to limit the impact if exploitation occurs. The vulnerability highlights the importance of proper header validation and the need for consistent security behavior across different content types in web browsers, emphasizing the critical nature of maintaining up-to-date security patches and following secure coding practices that prevent improper header handling.