Cisco Prime DCNM fmserver Servlet Directory Traversal Vulnerability (CVE-2015-0666) Technical Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTCisco Prime Data Center Network Manager (DCNM) versions prior to 7.1(1)
Unauthenticated remote attackers can read arbitrary system files by sending crafted HTTP requests containing directory traversal sequences
Immediately upgrade Cisco DCNM to version 7.1(1) or later, and restrict access to the DCNM management interface
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
To remediate this vulnerability, upgrade Cisco DCNM to version 7.1(1) or later. Below is an example procedure to verify the current version and apply the patch on a Linux-based DCNM appliance.
# Check DCNM service status and version
/etc/init.d/dcnm status
cat /usr/local/cisco/dcnm/etc/version
# Download and execute the secure installer (7.1(1) or later) from Cisco Portal
chmod +x dcnm-installer-v7.1.1.bin
./dcnm-installer-v7.1.1.bin --mode console2. Temporary Workaround & Hardening Configuration
If patching cannot be applied immediately, restrict access to the DCNM web management ports (e.g., TCP 80, 443, 8443) using a firewall or Web Application Firewall (WAF) to allow access only from trusted administrator IP addresses.
# Allow access to DCNM port only from a trusted admin IP (e.g., 192.168.10.50)
iptables -A INPUT -p tcp -s 192.168.10.50 --dport 8443 -j ACCEPT
# Block all other traffic to the DCNM port
iptables -A INPUT -p tcp --dport 8443 -j DROP3. Log Audit & IoC Verification Commands
Run the following commands on the DCNM server to inspect web access logs for directory traversal patterns targeting the fmserver servlet.
# Search for directory traversal patterns (.. or %2e%2e) in fmserver requests
grep -Ei 'fmserver.*(\.\./|\.\.\\|%2e%2e)' /usr/local/cisco/dcnm/logs/web_access*.log
# Search for attempts to access sensitive system files
grep -Ei '(etc/passwd|win.ini|boot.ini)' /usr/local/cisco/dcnm/logs/web_access*.logStop Exposing VPN Ports to the Internet — Switch to Zero-Trust Access
Eliminate public-facing VPN concentrators and firewall management ports with identity-first Zero-Trust Network Access.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2015-0666) is a classic Directory Traversal (CWE-22) flaw located within the fmserver servlet component of Cisco Prime Data Center Network Manager (DCNM). The root cause is the application's failure to properly sanitize and validate user-supplied input parameters representing file paths. Because the servlet does not filter out directory traversal sequences (such as ../ or ..\), it allows requests to escape the designated web root directory and access the underlying operating system's file system.
2. Exploitation Mechanics & Attack Scenario
An unauthenticated remote attacker can exploit this vulnerability by sending a specially crafted HTTP GET request to the vulnerable fmserver servlet endpoint. By embedding relative path traversal sequences (e.g., ../../../../etc/passwd on Linux or ../../../../Windows/win.ini on Windows) into the file-retrieval parameters, the attacker forces the application to resolve the path relative to the local file system. The servlet processes this request and returns the contents of the targeted file, allowing the attacker to read sensitive configuration files, credentials, and system logs without authentication.
3. Infrastructure & Business Impact
Cisco DCNM is a critical infrastructure management platform used to configure and monitor data center networks. A successful exploit allows attackers to harvest sensitive system information, which can be leveraged to conduct further high-impact attacks, such as privilege escalation, credential dumping, or lateral movement within the enterprise network. Given that this vulnerability is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, it represents a high-priority threat with active exploitation history in the wild.
Official Vendor Advisories & References
Directory traversal vulnerability in the fmserver servlet in Cisco Prime Data Center Network Manager (DCNM) before 7.1(1) allows remote attackers to read arbitrary files via a crafted pathname, aka Bug ID CSCus00241.
Frequently Asked SecOps Questions (CVE-2015-0666)
FAQQ1. How critical is CVE-2015-0666 and is it actively exploited in the wild?
CVE-2015-0666 is rated CVSS 7.5 (HIGH) with a 30-day EPSS exploitation probability of 40.4%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2015-0666?
Primary impacted vendors include cisco across prime data center network manager. Scope summary: All Cisco Prime Data Center Network Manager (DCNM) versions prior to 7.1(1) (Bug ID: CSCus00241)
Q3. What temporary mitigations or workarounds exist for CVE-2015-0666 before patching?
[Mitigation] Immediately upgrade Cisco DCNM to version 7.1(1) or later, and restrict access to the DCNM management interface Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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