Summary
ntpd NTS client denial of service via wrongly sized cookies
Two denial of service vulnerabilities were found in ntpd-rs related to the handling of NTS cookies in our client functionality. Whenever an NTS source is configured and the server behind that source is sending zero-sized cookies or cookies larger than what would fit in our buffer size, ntpd-rs would crash. Only configured NTS sources can abuse these vulnerabilities. NTP sources or third parties that are not configured cannot make use of these vulnerabilities.
For zero-sized cookies: a division by zero would force an exit when the number of new cookies that would need to be requested is calculated. In ntpd-rs 1.5.0 a check was added to prevent the division by zero.
For large cookies: while trying to send a NTP request with the cookie included, the buffer is too small to handle the cookie and an exit of ntpd-rs is forced once a write to the buffer is attempted. The memory outside the buffer would not be written to in this case. In ntpd-rs 1.5.0 a check was added that prevents accepting cookies larger than 350 bytes.
Users of older versions of ntpd-rs are recommended to update to the latest version. If an update is impossible, it is recommended to only add NTS sources to ntpd-rs that are trusted to not abuse this bug.
Impact
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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Frequently Asked Questions
- What is GHSA-V83Q-83HJ-RW38? GHSA-V83Q-83HJ-RW38 is a medium-severity security vulnerability in ntpd (rust), affecting versions < 1.5.0. It is fixed in 1.5.0.
- Which versions of ntpd are affected by GHSA-V83Q-83HJ-RW38? ntpd (rust) versions < 1.5.0 is affected.
- Is there a fix for GHSA-V83Q-83HJ-RW38? Yes. GHSA-V83Q-83HJ-RW38 is fixed in 1.5.0. Upgrade to this version or later.
- Is GHSA-V83Q-83HJ-RW38 exploitable, and should I be worried? Whether GHSA-V83Q-83HJ-RW38 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 GHSA-V83Q-83HJ-RW38 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 GHSA-V83Q-83HJ-RW38? Upgrade
ntpdto 1.5.0 or later.