CVE-2020-28200

Publication date 21 June 2021

Last updated 11 September 2024

Ubuntu priority

Cvss 3 Severity Score

The Sieve engine in Dovecot before 2.3.15 allows Uncontrolled Resource Consumption, as demonstrated by a situation with a complex regular expression for the regex extension.

Read the notes from the security team

Mitigation

Disabling the regex sieve extension avoids the worst problems. lmtp_user_concurrency_limit may also be helpful.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
dovecot	24.04 LTS noble	Not affected
	23.10 mantic	Not affected
	23.04 lunar	Not affected
	22.10 kinetic	Not affected
	22.04 LTS jammy	Not affected
	21.10 impish	Ignored end of life
	21.04 hirsute	Ignored end of life
	20.10 groovy	Ignored end of life
	20.04 LTS focal	Ignored
	18.04 LTS bionic	Ignored
	16.04 LTS xenial	Ignored
	14.04 LTS trusty	Ignored

Notes

mdeslaur

Per upstream, fixing this is a massive change that cannot be backported to earlier releases. As such, we will not be fixing this issue in older Ubuntu releases. Marking as ignored. For users of earlier releases, we recommend disabling the regex sieve extension.

Severity score breakdown

Parameter	Value
Base score	4.3 · Medium
Attack vector	Network
Attack complexity	Low
Privileges required	Low
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	None
Availability impact	Low
Vector	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L