CVE-2011-3200 in rsyslog
Summary
by MITRE
Stack-based buffer overflow in the parseLegacySyslogMsg function in tools/syslogd.c in rsyslogd in rsyslog 4.6.x before 4.6.8 and 5.2.0 through 5.8.4 might allow remote attackers to cause a denial of service (application exit) via a long TAG in a legacy syslog message.
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Analysis
by VulDB Data Team • 04/23/2025
The CVE-2011-3200 vulnerability represents a critical stack-based buffer overflow condition that affects the rsyslog daemon implementation. This flaw exists within the parseLegacySyslogMsg function located in the tools/syslogd.c file of rsyslog versions 4.6.x prior to 4.6.8 and 5.2.0 through 5.8.4. The vulnerability specifically targets the handling of legacy syslog messages where the TAG field exceeds the allocated buffer space, creating an exploitable condition that can be leveraged by remote attackers to disrupt system operations.
The technical implementation of this vulnerability stems from inadequate input validation within the syslog message parsing routine. When rsyslogd processes a legacy syslog message containing an excessively long TAG field, the parseLegacySyslogMsg function fails to properly bounds-check the input data before copying it into a fixed-size stack buffer. This classic buffer overflow scenario occurs because the code does not enforce length limitations on the TAG component, allowing an attacker to overwrite adjacent stack memory locations. The vulnerability is classified as CWE-121 Stack-based Buffer Overflow, which directly maps to the attack pattern described in the MITRE ATT&CK framework under the technique of Code Injection and Privilege Escalation.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable more sophisticated attack vectors. Remote attackers can exploit this weakness by sending specially crafted syslog messages with oversized TAG fields, causing the rsyslogd process to crash and terminate unexpectedly. This results in a denial of service condition that disrupts system logging capabilities and can potentially affect the availability of critical system monitoring functions. The vulnerability affects systems that rely on legacy syslog message formats, which were commonly used in network infrastructure and security monitoring environments where rsyslog serves as the primary syslog daemon implementation.
Mitigation strategies for CVE-2011-3200 primarily focus on immediate software updates and configuration hardening measures. Organizations should prioritize upgrading to rsyslog versions 4.6.8 or 5.8.5 and later, which contain the necessary patches to address the buffer overflow condition. Additionally, network administrators should implement input validation controls at network boundaries to filter out syslog messages with suspiciously long TAG fields. The implementation of proper access controls and monitoring of syslog message patterns can help detect potential exploitation attempts. From a defensive perspective, this vulnerability highlights the importance of maintaining up-to-date system components and implementing comprehensive security monitoring that can identify abnormal network traffic patterns associated with syslog message processing. The ATT&CK framework categorizes this as a system service disruption attack that can be mitigated through proper patch management and network segmentation controls.