Description
OpenBSD kernel version <= 6.5 can be forced to create long chains of TCP SACK holes that causes very expensive calls to tcp_sack_option() for every incoming SACK packet which can lead to a denial of service.
References (5)
Core 5
Core References
Patch, Third Party Advisory x_refsource_misc
https://github.com/openbsd/src/commit/ed8fdce754a5d8d14c09e989d8877707bd43906f
Exploit, Vendor Advisory x_refsource_misc
https://ftp.openbsd.org/pub/OpenBSD/patches/6.5/common/006_tcpsack.patch.sig
Third Party Advisory x_refsource_confirm
https://security.netapp.com/advisory/ntap-20190905-0001/
Exploit, Patch, Press/Media Coverage, Third Party Advisory x_refsource_misc
https://research.checkpoint.com/tcp-sack-security-issue-in-openbsd-cve-2019-8460/
Third Party Advisory, US Government Resource x_refsource_misc
https://us-cert.cisa.gov/ics/advisories/icsa-19-253-03
Scores
CVSS v3
7.5
EPSS
0.0069
EPSS Percentile
71.9%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Details
CWE
CWE-1049
Status
published
Products (1)
openbsd/openbsd
< 6.5
Published
Aug 26, 2019
Tracked Since
Feb 18, 2026