CVE-2005-2665 in Elm
Summary
by MITRE
Stack-based buffer overflow in expires.c in Elm 2.5 PL5 through PL7, and possibly other versions, allows remote attackers to execute arbitrary code via an e-mail message with a long Expires header.
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Analysis
by VulDB Data Team • 06/30/2025
The vulnerability identified as CVE-2005-2665 represents a critical stack-based buffer overflow flaw within the Elm email client software version 2.5 PL5 through PL7, with potential impact extending to other versions in the affected release series. This security weakness resides in the expires.c source file which processes email headers, specifically targeting the Expires header field that is commonly used in email messages to indicate when a message should be considered expired or no longer relevant. The flaw manifests when the email client encounters an email message containing an excessively long Expires header value, triggering a buffer overflow condition that can be exploited by remote attackers to execute arbitrary code on the targeted system.
The technical implementation of this vulnerability follows a classic stack-based buffer overflow pattern where the application fails to properly validate the length of input data before copying it into a fixed-size buffer allocated on the stack. When an attacker crafts an email message with an oversized Expires header, typically exceeding the buffer capacity allocated for header processing, the excess data overflows into adjacent memory locations, potentially corrupting the stack frame and overwriting critical execution data such as return addresses or function pointers. This memory corruption enables attackers to manipulate the program's execution flow and inject malicious code that executes with the privileges of the affected email client process.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a means to gain unauthorized access to systems running vulnerable versions of Elm. The attack vector is particularly concerning because it requires no authentication or special privileges from the attacker, making it a remote code execution vulnerability that can be exploited through standard email communication channels. Successful exploitation could result in complete system compromise, allowing attackers to establish persistent access, escalate privileges, or use the compromised system as a launching point for further attacks within the network infrastructure. The vulnerability's presence in multiple patch levels suggests a widespread issue affecting numerous installations of the Elm email client across various deployment environments.
Security professionals should note that this vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which is classified under the Common Weakness Enumeration framework as a fundamental flaw in memory management that continues to plague software applications. The exploitability characteristics of this vulnerability correspond to techniques described in the MITRE ATT&CK framework under the T1059.007 sub-technique for Command and Scripting Interpreter, specifically related to the execution of malicious code through buffer overflow exploitation. Organizations should prioritize immediate remediation through patch management, as the vulnerability's remote nature and code execution capabilities make it particularly dangerous. Additionally, implementing email filtering solutions that can detect and block malformed email headers, along with network segmentation and monitoring for suspicious email traffic patterns, can provide additional layers of defense against exploitation attempts targeting this specific vulnerability.