CVE-2020-28018

Publication date 4 May 2021

Last updated 25 August 2025

Ubuntu priority

Why this priority?

Cvss 3 Severity Score

Score breakdown

Description

Exim 4 before 4.94.2 allows Use After Free in smtp_reset in certain situations that may be common for builds with OpenSSL.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
exim4	22.04 LTS jammy	Fixed in 4.94-15ubuntu1.2
	21.10 impish	Fixed in 4.94-15ubuntu1.2
	21.04 hirsute	Fixed in 4.94-15ubuntu1.2
	20.10 groovy	Fixed in 4.94-7ubuntu1.2
	20.04 LTS focal	Fixed in 4.93-13ubuntu1.5
	18.04 LTS bionic	Fixed in 4.90.1-1ubuntu1.8
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

Notes

leosilva

trusty/xenial ESM not affected code introduced later

Severity score breakdown

CVSS version: CVSS v3.0

Base score 9.8 · Critical

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	High
Integrity impact	High
Availability impact	High

Scores

Parameter	Value
Base score	9.8 · Critical
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

USN-4934-1
Exim vulnerabilities
4 May 2021

Other references

https://www.cve.org/CVERecord?id=CVE-2020-28018

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