CVE-2011-1929 in Dovecot
Summary
by MITRE
lib-mail/message-header-parser.c in Dovecot 1.2.x before 1.2.17 and 2.0.x before 2.0.13 does not properly handle \0 characters in header names, which allows remote attackers to cause a denial of service (daemon crash or mailbox corruption) via a crafted e-mail message.
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Analysis
by VulDB Data Team • 11/07/2021
The vulnerability identified as CVE-2011-1929 represents a critical input validation flaw within the Dovecot email server's message header parsing functionality. This issue affects Dovecot versions 1.2.x prior to 1.2.17 and 2.0.x prior to 2.0.13, specifically targeting the lib-mail/message-header-parser.c component responsible for processing email headers. The flaw manifests when the parser encounters null characters within header names, creating a condition that can be exploited by remote attackers to disrupt normal email service operations.
The technical implementation of this vulnerability stems from inadequate sanitization of header name data during the parsing process. When Dovecot encounters a null character within an email header name, the parsing routine fails to properly handle this unexpected input, leading to undefined behavior that can result in daemon crashes or more severe mailbox corruption. This type of vulnerability falls under CWE-129, which addresses improper validation of input boundaries, and represents a classic case of buffer overread or improper input handling in email processing components. The null character injection allows attackers to manipulate the parsing logic in ways that were not anticipated during the development phase.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the integrity of email storage systems. Remote attackers can craft malicious email messages containing null characters in header names to trigger daemon crashes, forcing administrators to restart services and potentially causing temporary email service outages. In more severe cases, the corruption of mailbox data can result in permanent loss of email messages or the need for extensive data recovery procedures. This vulnerability particularly affects organizations relying on Dovecot as their primary email server solution, where the disruption of email services can have significant business implications.
Mitigation strategies for CVE-2011-1929 should prioritize immediate patching of affected Dovecot installations to versions 1.2.17 or 2.0.13, which contain the necessary fixes for proper null character handling in header names. Network administrators should implement email filtering mechanisms that can detect and quarantine suspicious header content before it reaches the Dovecot server. Additionally, monitoring systems should be configured to alert on unusual daemon crash patterns or mailbox corruption indicators that might suggest exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1499.004 for network denial of service and T1566.001 for spearphishing with attachments, highlighting the need for both defensive and detection capabilities. Organizations should also consider implementing email security appliances or services that provide additional layers of protection against malformed email content, particularly in environments where email traffic cannot be easily filtered at the network level.