GHSA-2xpx-vcmq-5f72
HIGHUnlimited number of NTS-KE connections can crash ntpd-rs server
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
ntpdReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Missing limit for accepted NTS-KE connections allows an unauthenticated remote attacker to crash ntpd-rs when an NTS-KE server is configured. Non NTS-KE server configurations, such as the default ntpd-rs configuration, are unaffected.
Details
Operating systems have a limit for the number of open file descriptors (which includes sockets) in a single process, e.g. 1024 on Linux by default. When ntpd-rs is configured as an NTS server, it accepts TCP connections for the NTS-KE service. If the process has reached the descriptor limit and tries to accept a new TCP connection, the accept() system call will return with the EMFILE error and cause ntpd-rs to abort.
A remote attacker can open a large number of parallel TCP connections to the server to trigger this crash. The connections need to be opened quickly enough to avoid the key-exchange-timeout-ms timeout (by default 1000 milliseconds).
Impact
Only NTS-KE server configuration are affected. Those without an NTS-KE server configuration such as NTS client only or NTP only configuration are unaffected. For affected configurations the ntpd-rs daemon can made completely unavailable by crashing the service. If ntpd-rs is automatically restarted, an attacker can repeat the attack to prevent ntpd-rs from doing anything useful.
Workarounds
- Disable NTS-KE server functionality
- Increase system resource limits (
RLIMIT_NOFILE) to make the attack more difficult - Lower the
key-exchange-timeout-msconfiguration setting to make the attack more difficult
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | ntpd | ≥ 0.3.1&&< 1.1.3 | 1.1.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ntpd. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update ntpd to 1.1.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2xpx-vcmq-5f72 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-2xpx-vcmq-5f72 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-2xpx-vcmq-5f72. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-2xpx-vcmq-5f72 in your dependencies?
O3 detects GHSA-2xpx-vcmq-5f72 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.