CVE-2018-21029

Publication date 30 October 2019

Last updated 24 July 2024

Ubuntu priority

Cvss 3 Severity Score

** DISPUTED ** systemd 239 through 245 accepts any certificate signed by a trusted certificate authority for DNS Over TLS. Server Name Indication (SNI) is not sent, and there is no hostname validation with the GnuTLS backend. NOTE: This has been disputed by the developer as not a vulnerability since hostname validation does not have anything to do with this issue (i.e. there is no hostname to be sent).

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
systemd	19.10 eoan	Not affected
	19.04 disco	Ignored end of life
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

Notes

mdeslaur

DNS over TLS not enabled by default in Ubuntu. this is only an issue in v243 because strict mode got introduced (DNSOverTLS=yes). Versions earlier than 243 only implemented opportunistic mode which, according to specs, might or not validate the resolver and can also be downgraded.

Severity score breakdown

Parameter	Value
Base score	9.8 · Critical
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	High
Integrity impact	High
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H