CVE-2021-38084

An issue was discovered in the POP3 component of Courier Mail Server before 1.1.5. Meddler-in-the...

8.1 HighFix available

An issue was discovered in the POP3 component of Courier Mail Server before 1.1.5. Meddler-in-the-middle attackers can pipeline commands after the POP3 STLS command, injecting plaintext commands into an encrypted user session.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

1.37%Up 0.7 points since Aug 4, 2021

What each source reports

NVD Score used 8.1

Record: CVE-2021-38084
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0: 6.8 MediumAV:N/AC:M/Au:N/C:P/I:P/A:P
Weakness: CWE-74
Updated: 2026-11-02

CVE List No score

Record: CVE-2021-38084
Updated: 2026-11-02

EUVDEUVD-2021-24557 No score

Record: EUVD-2021-24557
Updated: 2026-11-03

GitHub AdvisoriesGHSA-m7r5-gh9x-xg9m No score

An issue was discovered in the POP3 component of Courier Mail Server before 1.1.5. Meddler-in-the...

Record: GHSA-m7r5-gh9x-xg9m
Weakness: CWE-74
Updated: 2026-11-02

OSV 8.1

Record: CVE-2021-38084
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVDEBIAN-CVE-2021-38084 8.1

Record: DEBIAN-CVE-2021-38084
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVUBUNTU-CVE-2021-38084 8.1

Record: UBUNTU-CVE-2021-38084
CVSS 3.1: 8.1 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

Affected products

courier-mta courier mail server

Affected packages

Affected packages
Package	Affected	Fixed
`courier` Debian:12	All versions, plus listed versions 1.0.16-31.0.16-3.11.0.16-3.21.3.13-11.3.13-10 Show 30 moreShow less 1.3.13-111.3.13-21.3.13-31.3.13-41.3.13-51.3.13-61.3.13-71.3.13-81.3.13-91.4.1-11.4.1-101.4.1-21.4.1-31.4.1-41.4.1-51.4.1-61.4.1-71.4.1-81.4.1-91.5.1-11.5.1-21.5.1-31.5.1-42.0.2-12.0.2-22.0.2-32.0.2-42.0.3-12.0.3-22.0.6-1	None known
`courier` Debian:13	before 1.3.13-1	1.3.13-1
`courier` Debian:14	before 1.3.13-1	1.3.13-1
`courier` Ubuntu:16.04:LTS	All versions, plus listed versions 0.68.2-1ubuntu50.68.2-1ubuntu60.68.2-1ubuntu7	None known
`courier` Ubuntu:18.04:LTS	All versions, plus listed versions 0.78.0-20.78.0-2ubuntu10.78.0-2ubuntu2	None known
`courier` Ubuntu:20.04:LTS	All versions, plus listed versions 1.0.6-1build11.0.6-1build2	None known
`courier` Ubuntu:22.04:LTS	All versions, plus listed versions 1.0.16-3build11.0.16-3build21.0.16-3build3	None known
`courier` Ubuntu:25.10	All versions, plus listed versions 1.3.13-111.4.1-11.4.1-21.4.1-2build11.4.1-3	None known
`courier` Ubuntu:26.10	All versions, plus listed versions 1.5.1-21.5.1-42.0.6-1	None known
`courier` Ubuntu:26.04:LTS	All versions, plus listed versions 1.4.1-31.4.1-101.5.1-2	None known

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-38084 is a high vulnerability (CVSS 8.1) in Courier-mta Courier Mail Server, published August 3, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.37%, the 72nd percentile. Fixed in courier 1.3.13-1.