CVE-2010-1103 in Stainless
Summary
by MITRE
Integer overflow in Stainless 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 identified as CVE-2010-1103 represents a critical integer overflow flaw within the Stainless software framework that fundamentally compromises network security controls. This issue specifically affects the handling of outbound TCP connections where the software fails to properly validate port numbers against the constraints of the unsigned short data type. The vulnerability arises from insufficient input validation mechanisms that allow malicious actors to exploit the system's port restriction mechanisms through carefully crafted port values that exceed normal operational parameters.
The technical implementation of this vulnerability stems from the software's failure to perform proper bounds checking on port numbers during connection establishment processes. When a port number of 65561 is presented to the system, it exceeds the maximum value that can be represented by an unsigned short integer which is limited to 65535. This overflow condition creates a scenario where the system interprets the port number incorrectly, effectively bypassing the intended security controls that should restrict outbound connections to legitimate port ranges. The exploitation demonstrates how improper integer handling can lead to privilege escalation and unauthorized network access.
The operational impact of this vulnerability extends beyond simple port restriction bypass to encompass broader network security implications. Attackers can leverage this flaw to establish outbound connections through ports that should normally be blocked or restricted, potentially enabling unauthorized communication channels, data exfiltration, or the establishment of command and control connections. The vulnerability essentially allows attackers to circumvent network access control policies that rely on port-based restrictions, undermining the defensive posture of systems that depend on such controls for network segmentation and security enforcement.
Security professionals should recognize this vulnerability as a variant of CWE-190, Integer Overflow or Wraparound, which represents a well-documented class of vulnerabilities affecting software systems that fail to properly handle integer arithmetic operations. The attack vector aligns with techniques described in the ATT&CK framework under T1071.004 Application Layer Protocol: DNS and T1071.001 Application Layer Protocol: Web Protocols, where attackers exploit application-level flaws to establish unauthorized network connections. Organizations should implement immediate mitigations including input validation, code reviews focusing on integer handling, and network monitoring to detect anomalous port usage patterns that may indicate exploitation attempts.
Mitigation strategies should encompass both immediate code-level fixes and broader security architecture improvements. The primary solution involves implementing robust input validation that explicitly checks port numbers against valid ranges and prevents overflow conditions through proper data type handling. Additionally, network segmentation controls should be enhanced to include port-based monitoring and anomaly detection capabilities that can identify unusual outbound connection patterns. Regular security assessments should focus on identifying similar integer handling vulnerabilities across the software stack, as these flaws often manifest in multiple components and can provide attackers with persistent access vectors. The vulnerability serves as a reminder of the critical importance of proper integer arithmetic handling in security-sensitive applications and the need for comprehensive security testing that includes boundary condition validation.