CVE-2005-1911 in leafnode
Summary
by MITRE
The fetchnews NNTP client in leafnode 1.11.2 and earlier can hang while waiting for input that never arrives, which allows remote NNTP servers to cause a denial of service (news loss).
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Analysis
by VulDB Data Team • 06/07/2019
The vulnerability described in CVE-2005-1911 represents a classic denial of service flaw within the leafnode NNTP client software. This issue affects versions 1.11.2 and earlier of the leafnode package, which serves as a news client for retrieving Usenet news articles through the Network News Transfer Protocol. The flaw manifests when the fetchnews utility attempts to communicate with remote NNTP servers and becomes stuck in a waiting state for input that never materializes. This condition creates a scenario where legitimate news retrieval operations can be indefinitely blocked, effectively rendering the client unable to function properly for news acquisition.
The technical root cause of this vulnerability lies in the improper handling of network communication timeouts within the fetchnews client implementation. When establishing connections with NNTP servers, the software fails to implement adequate timeout mechanisms or input validation procedures that would detect when a remote server becomes unresponsive or fails to send expected data. This lack of proper error handling creates a race condition where the client thread remains indefinitely blocked waiting for data that will never arrive, causing the entire news fetching process to stall. The vulnerability specifically targets the input/output operations that occur during the news retrieval process, making it particularly dangerous for systems that rely on automated news fetching.
From an operational perspective, this vulnerability presents a significant risk to news servers and organizations that depend on automated news retrieval systems. Remote attackers can exploit this flaw by simply connecting to the vulnerable leafnode client and initiating a connection that never completes properly, causing the client to hang indefinitely. This results in a denial of service condition where legitimate news articles cannot be retrieved, leading to potential information loss and service disruption. The impact extends beyond simple unavailability as it can affect cascading systems that depend on timely news delivery, potentially causing downstream failures in news aggregation services, content distribution networks, or automated reporting systems that rely on leafnode for their news feeds.
The vulnerability aligns with CWE-400, which categorizes improper handling of network resources as a weakness leading to denial of service conditions. Additionally, this flaw demonstrates characteristics consistent with ATT&CK technique T1499.004, specifically the use of network disruption to deny services to legitimate users. Organizations implementing affected versions of leafnode should prioritize immediate patching to address this vulnerability, as the flaw can be exploited remotely without requiring authentication or special privileges. The recommended mitigation strategy involves upgrading to leafnode versions that include proper timeout handling and input validation mechanisms, ensuring that network operations do not remain indefinitely blocked. System administrators should also implement monitoring solutions to detect hanging processes and establish automated restart procedures for news client services to minimize service disruption. Furthermore, network segmentation and firewall rules can provide additional defense in depth by limiting exposure to potentially malicious NNTP servers while maintaining necessary connectivity for legitimate news services.