CVE-2023-27582: maddy is a composable, all-in-one mail server

This month

CRITICAL 9.1REMOTEUPGRADE

CVE-2023-27582 is a critical-severity flaw (CVSS 9.1) affecting maddy. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

maddy is a composable, all-in-one mail server. Starting with version 0.2.0 and prior to version 0.6.3, maddy allows a full authentication bypass if SASL authorization username is specified when using the PLAIN authentication mechanisms. Instead of validating the specified username, it is accepted as is after checking the credentials for the authentication username. maddy 0.6.3 includes the fix for the bug. There are no known workarounds.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 37%)
CISA exploited list	No
Weakness	CWE-287, CWE-305
Published	2023-03-13
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: maddy project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-03-13 22:15 UTCPublished CVE record published
2026-06-17 05:45 UTCUpdated Record last modified

maddy project maddy UPGRADE

Affected: >= 0.2.0 and < 0.6.3

Fixed in: 0.6.3

Safe to downgrade to: a release before 0.2.0

1. Check installed version

apt-cache policy maddy || rpm -q maddy || maddy --version

2. UPGRADE to 0.6.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade maddy

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade maddy

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 0.2.0 (Debian / Ubuntu)

apt-cache madison maddy sudo apt install maddy=<VERSION_BEFORE_0.2.0> sudo apt-mark hold maddy

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list maddy sudo dnf downgrade maddy-<VERSION_BEFORE_0.2.0> sudo dnf versionlock add maddy

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-27582?

maddy: upgrade to 0.6.3. Exact commands for each OS are on this page.

Is CVE-2023-27582 being exploited?

CVE-2023-27582 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-27582 affect?

CVE-2023-27582 affects maddy. Severity is critical (CVSS 9.1). maddy is a composable, all-in-one mail server. Starting with version 0.2.0 and prior to version 0.6.3, maddy allows a full authentication bypass if SASL authorization username is specified when using the PLAIN authentication mechanisms. Ins

How urgent is CVE-2023-27582?

Priority 53/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-40193 HIGH 8.2 UPGRADE maddy is a composable, all-in-one mail server
CVE-2022-24732 MEDIUM 6.3 UPGRADE Maddy Mail Server is an open source SMTP compatible email server
CVE-2021-42583 HIGH 7.5 UPGRADE A Broken or Risky Cryptographic Algorithm exists in Max Mazurov Maddy before 0.5.2, which is an unnecessary ri

References

← Back to latest CVEs