CVE-2010-1101 in iCab
Summary
by MITRE
Integer overflow in Alexander Clauss iCab allows remote attackers to bypass intended port restrictions on outbound TCP connections via a port number outside the range of the unsigned short data type, as demonstrated by a value of 65561 for TCP port 25.
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Analysis
by VulDB Data Team • 05/03/2026
The vulnerability described in CVE-2010-1101 represents a critical integer overflow flaw within Alexander Clauss iCab web browser software that fundamentally compromises network security controls. This issue specifically targets the handling of TCP port numbers during outbound connection attempts, creating a pathway for malicious actors to circumvent established security policies and access restricted network resources. The vulnerability manifests when the software processes port numbers that exceed the maximum value permissible for unsigned short data types, which is 65535, thereby triggering unexpected behavior in the network connection logic.
The technical exploitation of this vulnerability relies on the manipulation of TCP port values that fall outside the normal range of 0-65535, with the demonstration showing a port value of 65561 being used against TCP port 25. This overflow condition occurs because the application fails to properly validate or constrain port number inputs, allowing an attacker to specify a value that, when processed, wraps around or overflows the unsigned short data type boundaries. The flaw essentially creates a bypass mechanism where the software's intended port restriction policies become ineffective, enabling unauthorized access to network services that should remain protected.
From an operational standpoint, this vulnerability poses significant risks to organizations relying on iCab for web browsing activities, particularly in environments where network segmentation and port-based access controls are implemented. The ability to bypass port restrictions means that attackers could potentially access restricted services, establish unauthorized connections to internal systems, or circumvent firewall rules that depend on port-based filtering mechanisms. This vulnerability directly impacts the integrity of network security policies and can lead to unauthorized data access, service disruption, or even lateral movement within compromised networks.
The underlying weakness aligns with CWE-190, which catalogs integer overflow and wraparound vulnerabilities that occur when operations on integer values exceed their maximum or minimum representable values. This classification indicates that the vulnerability stems from inadequate input validation and improper handling of data type boundaries within the application's network processing code. The exploitability of this condition is further enhanced by ATT&CK technique T1071.004, which covers application layer protocol manipulation, as attackers can leverage this flaw to manipulate network communications and bypass security controls.
Effective mitigation strategies for this vulnerability require immediate patching of the iCab software to address the integer overflow condition in port number handling. Organizations should implement network segmentation and firewall rules that provide additional layers of protection beyond the application-level controls, ensuring that even if the application fails to enforce port restrictions, network infrastructure can still prevent unauthorized connections. Input validation measures should be strengthened at all levels of the application stack to prevent malformed port numbers from being processed, while regular security assessments should verify that similar integer handling issues do not exist in other components of the network infrastructure.