FreeBSD : FreeBSD -- TCP IPv6 SYN cache kernel information disclosure (0e06013e-6a06-11ea-92ab-00163e433440)

medium Nessus Plugin ID 134720


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The remote FreeBSD host is missing one or more security-related updates.


When a TCP server transmits or retransmits a TCP SYN-ACK segment over IPv6, the Traffic Class field is not initialized. This also applies to challenge ACK segments, which are sent in response to received RST segments during the TCP connection setup phase. Impact : For each TCP SYN-ACK (or challenge TCP-ACK) segment sent over IPv6, one byte of kernel memory is transmitted over the network.


Update the affected packages.

See Also

Plugin Details

Severity: Medium

ID: 134720

File Name: freebsd_pkg_0e06013e6a0611ea92ab00163e433440.nasl

Version: 1.3

Type: local

Published: 3/20/2020

Updated: 5/8/2020

Dependencies: ssh_get_info.nasl

Configuration: Enable paranoid mode

Risk Information

CVSS Score Source: CVE-2020-7451


Risk Factor: Low

Score: 1.4


Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

Vector: AV:N/AC:L/Au:N/C:P/I:N/A:N

Temporal Vector: E:U/RL:OF/RC:C


Risk Factor: Medium

Base Score: 5.3

Temporal Score: 4.6

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Temporal Vector: E:U/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:freebsd:freebsd:FreeBSD, cpe:/o:freebsd:freebsd

Required KB Items: Host/local_checks_enabled, Host/FreeBSD/release, Host/FreeBSD/pkg_info, Settings/ParanoidReport

Exploit Ease: No known exploits are available

Patch Publication Date: 3/19/2020

Vulnerability Publication Date: 3/19/2020

Reference Information

CVE: CVE-2020-7451

FreeBSD: SA-20:04.tcp