CVE-2007-0199 in IOS
Summary
by MITRE
The Data-link Switching (DLSw) feature in Cisco IOS 11.0 through 12.4 allows remote attackers to cause a denial of service (device reload) via "an invalid value in a DLSw message... during the capabilities exchange."
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Analysis
by VulDB Data Team • 06/14/2025
The vulnerability identified as CVE-2007-0199 resides within Cisco IOS implementations from version 11.0 through 12.4, specifically affecting the Data-link Switching DLSw feature. This represents a critical denial of service weakness that can be exploited by remote attackers to forcibly reboot network devices. The flaw manifests during the capabilities exchange phase of DLSw communication, where malformed or invalid values in DLSw messages trigger unexpected behavior in the affected Cisco IOS versions. This vulnerability directly impacts the stability and availability of network infrastructure, as successful exploitation results in complete device reload operations that can disrupt network services and require manual intervention to restore normal operations.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and more specifically with CWE-129, concerning invalid input validation. The root cause stems from inadequate input validation mechanisms within the DLSw implementation, where the system fails to properly sanitize or validate incoming DLSw messages during the capabilities exchange process. When an attacker crafts and sends a DLSw message containing invalid values, the IOS software does not adequately handle these malformed inputs, leading to unpredictable behavior that ultimately results in system reload operations. This type of vulnerability represents a classic example of insufficient validation of input data, where the software assumes that incoming network traffic will conform to expected formats without proper verification mechanisms.
The operational impact of CVE-2007-0199 extends beyond simple service disruption to encompass potential network-wide consequences. When exploited, this vulnerability can cause cascading failures across interconnected network devices that rely on DLSw functionality for communication between different network segments. The remote exploitation capability means that attackers do not require physical access or network proximity to trigger the vulnerability, making it particularly dangerous in environments where network security is paramount. Organizations may experience unplanned outages, service degradation, and potential loss of network visibility during the device restart process, which can have significant business implications depending on the criticality of the affected network infrastructure.
Mitigation strategies for this vulnerability should include immediate implementation of Cisco IOS patches and updates that address the specific input validation flaws in the DLSw implementation. Network administrators should also consider disabling DLSw functionality on affected devices when it is not actively required, as this removes the attack surface entirely. The implementation of network access control lists and firewall rules that filter DLSw traffic can provide additional protection layers, though these measures are less effective than proper software patches. Organizations should also implement monitoring solutions that can detect unusual DLSw message patterns or device restart events that may indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to technique T1499.004 for network denial of service and T1566.002 for phishing with malicious attachments, as attackers may use this weakness to disrupt network availability as part of broader attack campaigns. The vulnerability demonstrates the importance of maintaining up-to-date network device firmware and implementing robust input validation practices throughout network infrastructure components.