CVE-2010-1167 in fetchmail
Summary
by MITRE
fetchmail 4.6.3 through 6.3.16, when debug mode is enabled, does not properly handle invalid characters in a multi-character locale, which allows remote attackers to cause a denial of service (memory consumption and application crash) via a crafted (1) message header or (2) POP3 UIDL list.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 01/26/2025
The vulnerability identified as CVE-2010-1167 affects fetchmail versions ranging from 4.6.3 through 6.3.16 and represents a significant security flaw that exploits improper handling of character encoding in debug mode. This vulnerability falls under the category of denial of service attacks and specifically targets the application's memory management and processing capabilities when encountering malformed input data. The flaw manifests when fetchmail operates in debug mode and processes messages containing invalid characters within multi-character locales, creating a scenario where legitimate application functionality becomes compromised through malicious input manipulation.
The technical exploitation of this vulnerability occurs through carefully crafted message headers or POP3 UIDL lists that contain invalid character sequences. When fetchmail processes these malformed inputs while debug mode is enabled, the application fails to properly sanitize or handle the unexpected character data, leading to excessive memory consumption and eventual application crashes. This behavior represents a classic buffer overread or improper input validation scenario where the application's character processing routines do not adequately account for locale-specific character encodings and their potential to cause memory corruption or resource exhaustion. The vulnerability is particularly dangerous because it can be triggered remotely without requiring authentication, making it an attractive target for automated attacks.
The operational impact of CVE-2010-1167 extends beyond simple service disruption to potentially compromise system availability and stability in environments where fetchmail serves as a critical email retrieval mechanism. Organizations relying on fetchmail for automated email processing or mail server operations may experience significant downtime when this vulnerability is exploited, particularly in high-volume email environments where the application processes numerous messages regularly. The memory consumption aspect of this vulnerability means that systems could experience gradual resource depletion until complete system failure occurs, while the application crash component results in immediate service interruption. This vulnerability aligns with CWE-129 and CWE-704 categories related to improper input validation and memory corruption issues, and it maps to ATT&CK technique T1499.004 for denial of service through resource exhaustion.
Mitigation strategies for CVE-2010-1167 should focus on immediate patching of affected fetchmail versions to the latest stable releases that contain proper character handling and input validation routines. Organizations should disable debug mode in production environments where this vulnerability exists, as the flaw specifically requires debug mode to be enabled for exploitation. Network-level protections can include implementing email filtering rules that sanitize message headers and UIDL lists before they reach fetchmail processing, though this approach provides only partial protection. System administrators should also consider implementing monitoring solutions that can detect unusual memory consumption patterns or application crash events that may indicate exploitation attempts. The vulnerability demonstrates the importance of proper internationalization and locale handling in network applications, particularly those processing user-supplied data, and serves as a reminder of the critical need for robust input validation in all application components. Organizations should also implement regular vulnerability assessments and security updates to prevent similar issues from arising in other components of their email infrastructure.