CVE-2015-8158 Ntp CVE debrief

Who should care

Operators and security teams managing systems that include ntpq/NTP, especially where NTP clients or monitoring hosts may be reachable from untrusted networks or where package versions may lag behind vendor-fixed releases.

Technical summary

According to the CVE description, the vulnerability is in ntpq's getresponse function. Crafted packets with incorrect values can cause the function to loop indefinitely, resulting in a remote denial of service. The supplied NVD vector classifies the issue as network-exploitable, with no privileges required, no user interaction, and availability impact only. Fixed versions are identified in the CVE description as 4.2.8p9 and 4.3.90.

Defensive priority

Medium priority. The impact is availability-only, but the issue is remotely triggerable and unauthenticated, so exposed NTP deployments should be checked and patched promptly.

Recommended defensive actions

• Verify the installed NTP version and upgrade to 4.2.8p9 or later, or 4.3.90 or later, as applicable.
• Use the NTP project advisory and downstream vendor advisories to confirm package-specific fixed builds.
• Audit systems that run ntpq or ship NTP components to ensure the vulnerable release line is not present.
• If immediate upgrading is not possible, restrict exposure to untrusted networks and monitor for abnormal ntpq/NTP behavior.

Evidence notes

The vulnerability description states that getresponse in ntpq can enter an infinite loop when processing crafted packets with incorrect values, enabling remote denial of service. The NVD record assigns CVSS 5.9/MEDIUM and a vector with network attack, no privileges, no user interaction, and availability impact only. The reference set includes the NTP project advisory plus downstream advisories from vendors such as Red Hat and Debian, which support the remediation guidance.

Official resources