CVE-2025-6188 Overview
A network protocol vulnerability has been identified in Arista EOS where maliciously formed UDP packets with source port 3503 may be improperly accepted by the operating system. UDP Port 3503 is associated with LspPing Echo Reply functionality. This vulnerability enables authentication bypass through packet spoofing, which can result in unexpected behaviors, especially for UDP-based services that do not perform their own form of authentication.
Critical Impact
Network-accessible attackers can send specially crafted UDP packets to affected Arista EOS platforms, potentially bypassing authentication mechanisms and manipulating UDP-based services without requiring user interaction or privileges.
Affected Products
- Arista EOS (affected platforms)
- Network devices running vulnerable Arista EOS versions
- UDP-based services on affected Arista infrastructure
Discovery Timeline
- 2025-08-25 - CVE CVE-2025-6188 published to NVD
- 2025-08-27 - Last updated in NVD database
Technical Details for CVE-2025-6188
Vulnerability Analysis
This vulnerability is classified under CWE-290 (Authentication Bypass by Spoofing), indicating a fundamental weakness in how Arista EOS validates the authenticity of incoming network packets. The system fails to properly verify the legitimacy of UDP packets originating from source port 3503, which is reserved for LspPing Echo Reply functionality in MPLS networks.
The core issue lies in the trust relationship established between the network stack and packets arriving on this specific port. Without adequate validation, an attacker can craft packets that appear to originate from legitimate LspPing sources, causing the system to process these packets as authentic communications.
Root Cause
The root cause is an authentication bypass through spoofing vulnerability where Arista EOS does not implement sufficient validation mechanisms for UDP packets arriving with source port 3503. The LspPing Echo Reply port is implicitly trusted, allowing malicious actors to inject arbitrary UDP packets that the system accepts without proper authentication verification. This design flaw is particularly impactful for UDP-based services that rely on network-level controls rather than implementing application-layer authentication.
Attack Vector
The attack is network-accessible and requires no user interaction or special privileges to execute. An attacker can exploit this vulnerability by:
- Crafting UDP packets with source port 3503 set in the header
- Directing these malformed packets to the target Arista EOS device
- Exploiting the system's implicit trust of packets from this port
- Manipulating UDP-based services that lack additional authentication layers
The network-based attack vector combined with low attack complexity makes this vulnerability particularly concerning for organizations with internet-facing Arista infrastructure. Since the vulnerability affects integrity but not confidentiality or availability directly, attackers can potentially manipulate service behavior or inject unauthorized data into UDP-based communications.
Detection Methods for CVE-2025-6188
Indicators of Compromise
- Unusual volume of UDP traffic originating from source port 3503 from external or unexpected sources
- Anomalous LspPing Echo Reply packets that do not correlate with legitimate MPLS testing activities
- Unexpected behavior in UDP-based services following receipt of traffic on port 3503
- Log entries indicating acceptance of UDP packets from untrusted network segments
Detection Strategies
- Implement network monitoring to detect UDP packets with source port 3503 from non-authorized sources
- Deploy intrusion detection systems (IDS) with rules to flag suspicious LspPing traffic patterns
- Enable detailed logging on Arista EOS devices to capture UDP packet acceptance events
- Monitor for deviation from baseline LspPing traffic patterns in your MPLS environment
Monitoring Recommendations
- Establish baselines for legitimate LspPing Echo Reply traffic in your network
- Configure alerts for UDP port 3503 traffic originating from external networks or unauthorized internal segments
- Implement continuous monitoring of affected Arista EOS devices for configuration changes or anomalous behavior
- Review network flow data regularly for signs of spoofed UDP traffic targeting critical infrastructure
How to Mitigate CVE-2025-6188
Immediate Actions Required
- Review the Arista Security Advisory #0121 for specific remediation guidance
- Implement network-level access controls to restrict traffic to UDP port 3503 from trusted sources only
- Ensure UDP-based services implement their own authentication mechanisms rather than relying solely on network controls
- Audit network configurations to identify affected Arista EOS platforms in your environment
Patch Information
Arista has released security advisory documentation addressing this vulnerability. Organizations should consult the Arista Security Advisory #0121 for specific patch availability, affected version information, and upgrade instructions. Contact Arista support or your account representative for assistance identifying the appropriate patched version for your deployment.
Workarounds
- Apply access control lists (ACLs) to filter UDP packets with source port 3503 from untrusted network segments
- Implement firewall rules to restrict LspPing traffic to only authorized network management systems
- Enable rate limiting on UDP port 3503 to reduce the impact of potential exploitation attempts
- Consider disabling LspPing functionality if not required for MPLS operations in your environment
# Example ACL configuration concept for Arista EOS
# Consult Arista documentation for exact syntax and verify in lab environment
# This restricts UDP source port 3503 to trusted management subnet only
ip access-list extended PROTECT-LSPPING
permit udp 10.0.0.0/24 any eq 3503
deny udp any any eq 3503 log
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
