CVE-2019-5599 — In FreeBSD 12

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

01What is this vulnerability?

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.

02Affected products

Vendor	Product	Versions
n	a / FreeBSD	FreeBSD 12.0 before 12.0-RELEASE-p6

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2019-07-02T20:02:17.000Z
• Last modified: 2024-08-04T20:01:51.990Z

09References

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