CVE-2023-33192: Improper handling of NTS cookie length that could crash the ntpd-rs server

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-05-27 · updated 2026-06-17
Weakness: CWE-130

Description

ntpd-rs is an NTP implementation written in Rust. 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. 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.

Affected products

pendulum-project ntpd-rs: from 0.3.0 before 0.3.3 — fixed in 0.3.3

How to fix

Upgrade to a fixed version: pendulum-project ntpd-rs 0.3.3. Check the vendor advisory for mitigations.

References

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