CVE-2008-1996 in licq
Summary
by MITRE
licq before 1.3.6 allows remote attackers to cause a denial of service (file-descriptor exhaustion and application crash) via a large number of connections.
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Analysis
by VulDB Data Team • 12/25/2025
The vulnerability identified as CVE-2008-1996 affects licq versions prior to 1.3.6, representing a significant security flaw that enables remote attackers to execute denial of service attacks against affected systems. This issue specifically targets the connection handling mechanisms within the licq instant messaging client, which is a popular application for connecting to AIM and other instant messaging networks. The vulnerability stems from inadequate resource management and connection handling logic that fails to properly terminate or limit incoming connections.
The technical flaw manifests when an attacker establishes a large number of simultaneous connections to the licq service, exploiting the application's inability to efficiently manage these connections. This results in file descriptor exhaustion, where the system runs out of available file descriptors necessary for maintaining network connections and other I/O operations. The flaw operates at the system level where each connection consumes a file descriptor, and without proper connection limits or cleanup mechanisms, the application becomes overwhelmed and eventually crashes. This represents a classic resource exhaustion attack pattern that falls under CWE-400, which specifically addresses unchecked resource consumption in software applications.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the overall stability of systems running affected licq versions. When file descriptors are exhausted, the application becomes unresponsive and crashes, requiring manual intervention to restore normal operations. This affects not only the immediate availability of the messaging service but can also impact other applications that depend on the same system resources. The vulnerability is particularly dangerous in environments where licq serves as a communication channel, as it can be exploited to deny legitimate users access to critical messaging services.
Mitigation strategies for this vulnerability require immediate patching of affected licq installations to version 1.3.6 or later, which includes enhanced connection handling and resource management features. System administrators should also implement connection rate limiting and monitoring to detect unusual connection patterns that may indicate exploitation attempts. Network-level controls such as firewall rules and connection tracking can provide additional defense in depth. The ATT&CK framework categorizes this type of attack under T1499, which covers network denial of service, and T1566, which addresses initial access through social engineering or exploitation of vulnerable services. Organizations should also consider implementing automated monitoring solutions that can detect and alert on excessive connection attempts, as well as regular security assessments to identify similar vulnerabilities in other network services that may exhibit similar resource management flaws.