Summary
Improper handling of NTS cookie length that could crash the ntpd-rs server
Workarounds
ntpd-rs running purely as an ntp client is not affected. By default, ntpd-rs packages are not configured to run as a server.
For machines where serving the time is required, there is no known workaround. Users are recommended to upgrade ntpd-rs as soon as possible.
References
https://github.com/pendulum-project/ntpd-rs/pull/752
We would like to thank @mlichvar for identifying this issue
Impact
ntpd-rs does not validate the length of NTS cookies in received NTP packets to the server. An attacker can crash the server by sending a specially crafted NTP packet containing a cookie shorter than what the server expects. The server also crashes when it is not configured to handle NTS packets.
ntpd-rs running purely as an ntp client is not affected.
CVE-2023-33192 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.3.3); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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The issue was caused by improper slice indexing. The indexing operations were replaced by safer alternatives that do not crash the ntpd-rs server process but instead properly handle the error condition. A patch was released in version 0.3.3
Frequently Asked Questions
- What is CVE-2023-33192? CVE-2023-33192 is a high-severity security vulnerability in ntpd (rust), affecting versions >= 0.3.0, < 0.3.3. It is fixed in 0.3.3.
- How severe is CVE-2023-33192? CVE-2023-33192 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of ntpd are affected by CVE-2023-33192? ntpd (rust) versions >= 0.3.0, < 0.3.3 is affected.
- Is there a fix for CVE-2023-33192? Yes. CVE-2023-33192 is fixed in 0.3.3. Upgrade to this version or later.
- Is CVE-2023-33192 exploitable, and should I be worried? Whether CVE-2023-33192 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-33192 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2023-33192? Upgrade
ntpdto 0.3.3 or later.