CVE-1999-1175 in IOS
Summary
by MITRE
Web Cache Control Protocol (WCCP) in Cisco Cache Engine for Cisco IOS 11.2 and earlier does not use authentication, which allows remote attackers to redirect HTTP traffic to arbitrary hosts via WCCP packets to UDP port 2048.
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Analysis
by VulDB Data Team • 04/20/2026
The vulnerability identified as CVE-1999-1175 represents a critical security flaw in Cisco's Web Cache Control Protocol implementation within the Cisco Cache Engine running Cisco IOS version 11.2 and earlier. This weakness stems from the absence of proper authentication mechanisms within the WCCP protocol, which is designed to facilitate communication between routers and cache engines in web caching environments. The vulnerability specifically affects the Cisco Cache Engine implementation where WCCP packets are processed on UDP port 2048, creating an exploitable entry point for malicious actors seeking to manipulate network traffic routing.
The technical exploitation of this vulnerability occurs through the manipulation of WCCP packets that are transmitted over UDP port 2048. Without authentication mechanisms in place, any remote attacker capable of sending packets to this port can potentially redirect HTTP traffic to arbitrary hosts within the network. This flaw directly violates fundamental security principles of network protocol design and represents a classic case of insufficient authentication as outlined in CWE-305. The vulnerability allows for unauthorized traffic redirection, effectively enabling man-in-the-middle attacks where malicious actors can intercept and redirect web traffic to compromised servers or malicious endpoints.
The operational impact of this vulnerability extends beyond simple traffic redirection, creating significant risks for network security and data integrity. Organizations utilizing affected Cisco Cache Engine implementations face potential exposure to traffic interception, content manipulation, and unauthorized access to sensitive web resources. The vulnerability can be exploited to redirect users to phishing sites, malware distribution points, or to intercept sensitive information transmitted over HTTP connections. This weakness undermines the trust model of web caching infrastructure and can lead to widespread compromise of user sessions and data confidentiality. According to ATT&CK framework, this vulnerability maps to T1071.004 for application layer protocol and T1566 for phishing, as attackers can leverage this to redirect traffic to malicious endpoints.
Mitigation strategies for CVE-1999-1175 require immediate implementation of network segmentation and access control measures to restrict communication on UDP port 2048. Organizations should deploy firewall rules to block unauthorized access to this port from external networks and implement network access control lists to limit which devices can communicate with the cache engine. The most effective long-term solution involves upgrading to Cisco IOS versions that properly implement WCCP authentication mechanisms and support secure protocol implementations. Network administrators should also consider implementing network monitoring to detect anomalous WCCP traffic patterns and establish baseline behavior for cache engine communications. Additionally, organizations should conduct comprehensive network assessments to identify all instances of affected Cisco Cache Engine implementations and ensure proper patch management protocols are in place to address similar vulnerabilities in network infrastructure components.