CVE-2000-0415 in Outlook
Summary
by MITRE
Buffer overflow in Outlook Express 4.x allows attackers to cause a denial of service via a mail or news message that has a .jpg or .bmp attachment with a long file name.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability identified as CVE-2000-0415 represents a classic buffer overflow flaw within Microsoft Outlook Express version 4.x that specifically targets the handling of image file attachments. This security weakness manifests when the email client processes mail or news messages containing .jpg or .bmp attachments with excessively long filenames. The buffer overflow occurs in the client-side processing logic that parses and displays these multimedia attachments, creating an exploitable condition that can be leveraged by malicious actors to disrupt normal email operations.
The technical implementation of this vulnerability stems from inadequate input validation and boundary checking within the Outlook Express attachment processing subsystem. When the application encounters an attachment with a filename exceeding predetermined buffer limits, the excessive data overflows into adjacent memory regions, potentially corrupting critical program structures or executing arbitrary code. This flaw operates at the application layer and specifically affects the email client's ability to safely handle file name inputs, making it particularly dangerous in environments where users frequently receive attachments from untrusted sources.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it can potentially enable more sophisticated attacks depending on the execution environment and system configuration. An attacker could craft malicious email messages with deliberately oversized filenames to trigger the buffer overflow, causing Outlook Express to crash and terminate unexpectedly. This disruption affects user productivity and can potentially be exploited to deliver additional payloads or establish persistent access to compromised systems, particularly when combined with other vulnerabilities in the email client stack.
Security professionals should note that this vulnerability aligns with CWE-121, which categorizes buffer overflow conditions in stack-based buffers, and demonstrates how improper input handling can lead to system instability and potential privilege escalation. The ATT&CK framework would classify this as a denial of service attack vector that may be used as a precursor to more advanced exploitation techniques, particularly in targeting client-side applications that process untrusted data. Organizations should implement immediate mitigation strategies including email filtering rules that block suspicious attachments, user education regarding unsafe file handling practices, and prompt application updates to patched versions that address the buffer overflow conditions in Outlook Express 4.x.