CVE-2008-0027: Cisco Unified Communications Manager CTL Provider heap buffer overflow

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 19 September 2026. Confidence: medium.

critical priorityCVSS 2.0 base score of 10 with network reachability, no authentication, and complete confidentiality, integrity, and availability impact, combined with a high EPSS percentile, warrants critical priority despite the absence of KEV listing.

What it is

The Certificate Trust List (CTL) Provider service (CTLProvider.exe) in Cisco Unified Communications Manager and CallManager contains a heap-based buffer overflow triggered by a long request. A remote, unauthenticated attacker can crash the service or potentially execute arbitrary code on the affected system.

Impact

An attacker can cause a denial of service against the CTL Provider service or execute arbitrary code with the privileges of that service, which could lead to full compromise of the host.

Attack surface

The flaw is reachable over the network via the CTL Provider service listening on the affected CUCM/CallManager systems; the CVSS vector (AV:N/AC:L/Au:N) indicates no authentication and no user interaction are required.

Exploitation

The record is not listed in CISA KEV and no reference is tagged as exploit code, but EPSS is high (0.571, 99th percentile), indicating elevated likelihood of exploitation activity.

What to do

• Apply the Cisco vendor patch referenced in the advisory (CUCM 4.2(3)SR3, 4.3(1)SR1, CallManager 4.1(3)SR5c or later).
• Restrict network access to the CTL Provider service (TCP 2444) to trusted management hosts only.
• Segment or firewall CUCM management interfaces away from untrusted networks.
• Monitor for and investigate unexpected crashes or restarts of CTLProvider.exe.
• If patching is delayed, disable the CTL Provider service where operationally feasible.

Detection

• Monitor CTLProvider.exe process crashes or service restarts on CUCM hosts.
• Alert on anomalous or oversized requests to the CTL Provider service port from untrusted sources.
• Review network logs for scanning or connection attempts to the CTL Provider service from external addresses.
• Correlate host and network telemetry for signs of code execution following a CTL Provider crash.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.