CVE-2001-1263 in Interaccess
Summary
by MITRE
telnet95.exe in Pragma InterAccess 4.0 build 5 allows remote attackers to cause a denial of service (crash) via a large number of characters to port 23, possibly due to a buffer overflow.
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Analysis
by VulDB Data Team • 09/27/2025
The vulnerability identified as CVE-2001-1263 affects telnet95.exe component within Pragma InterAccess 4.0 build 5, representing a critical security flaw that enables remote attackers to execute denial of service attacks against systems running this specific telnet implementation. This vulnerability specifically targets the telnet service listening on port 23, which serves as the standard communication port for telnet protocol connections. The flaw manifests when an attacker sends an excessive number of characters to the telnet service, causing the application to crash and terminate unexpectedly. This behavior constitutes a classic buffer overflow vulnerability where the application fails to properly validate input length before processing incoming data, leading to memory corruption that ultimately results in service disruption.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the telnet95.exe binary. When the service receives data on port 23, it attempts to process the incoming character stream without sufficient bounds checking or buffer size limitations. This allows an attacker to overwhelm the application's memory buffers with excessive data, causing stack corruption or heap overflow conditions that lead to application termination. The vulnerability operates at the protocol level, leveraging the fundamental nature of telnet communication where data flows continuously through the established connection. This flaw directly maps to CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which addresses stack-based buffer overflow scenarios. The attack vector requires minimal sophistication as it only necessitates sending malformed data to the target port, making it particularly dangerous for systems that rely on telnet services for administrative access.
The operational impact of CVE-2001-1263 extends beyond simple service disruption to potentially compromise system availability and integrity within network infrastructure. Organizations utilizing Pragma InterAccess 4.0 may experience complete service outages when attackers exploit this vulnerability, particularly in environments where telnet services remain active for legacy system administration. The vulnerability affects systems where telnet95.exe is deployed as a service, potentially impacting critical network operations that depend on remote access capabilities. From an operational security perspective, this vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and T1566.001, representing spearphishing with embedded attachments that could potentially deliver exploitation payloads. The impact is particularly severe in environments where administrators rely on telnet for system maintenance, as the service disruption could prevent legitimate users from accessing critical systems during the attack window.
Mitigation strategies for this vulnerability require immediate implementation of network-level protections and application-specific fixes. Organizations should disable or remove the vulnerable telnet95.exe service from production environments where possible, as the telnet protocol itself presents numerous security risks beyond this specific vulnerability. Network administrators should implement firewall rules to restrict access to port 23 from untrusted networks and consider deploying intrusion detection systems that can identify abnormal traffic patterns associated with buffer overflow attempts. The most effective long-term solution involves upgrading to newer versions of the Pragma InterAccess software that address this specific buffer overflow condition through proper input validation and memory management practices. Additionally, implementing rate limiting and connection throttling mechanisms can help reduce the effectiveness of automated exploitation attempts while providing time for proper patch deployment. Security teams should also conduct comprehensive vulnerability assessments to identify other instances of legacy telnet implementations that may present similar risks, ensuring that all remote access services meet current security standards and operational requirements.