CVE-2026-24031: Dovecot SQL based authentication can be bypassed when auth_username_chars is cleared by admin

Q: How do I fix CVE-2026-24031?

dovecot: upgrade to 2.4.3; dovecot: upgrade to 3.1.4. Exact commands for each OS are on this page.

Q: Is CVE-2026-24031 being exploited?

CVE-2026-24031 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-24031 affect?

CVE-2026-24031 affects dovecot, dovecot. Severity is high (CVSS 7.7). Dovecot SQL based authentication can be bypassed when auth_username_chars is cleared by admin. This vulnerability allows bypassing authentication for any user and user enumeration. Do not clear auth_username_chars. If this is not possible,

Q: How urgent is CVE-2026-24031?

Priority 40/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.7REMOTEUPGRADEUPGRADE

CVE-2026-24031 is a high-severity flaw (CVSS 7.7) affecting dovecot, dovecot. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Dovecot SQL based authentication can be bypassed when auth_username_chars is cleared by admin. This vulnerability allows bypassing authentication for any user and user enumeration. Do not clear auth_username_chars. If this is not possible, install latest fixed version. No publicly available exploits are known.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.7 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 66%)
CISA exploited list	No
Weakness	CWE-89
Published	2026-03-27
Last modified	2026-10-26

Publisher (CNA): Open-Xchange · Vendor: dovecot · open-xchange

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-27 09:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

dovecot dovecot UPGRADE

Affected: < 2.4.3

Fixed in: 2.4.3

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 2.4.3 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade dovecot

Note

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

open-xchange dovecot UPGRADE

Affected: < 3.1.4

Fixed in: 3.1.4

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 3.1.4 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade dovecot

Note

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

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-2026-24031?

dovecot: upgrade to 2.4.3; dovecot: upgrade to 3.1.4. Exact commands for each OS are on this page.

Is CVE-2026-24031 being exploited?

CVE-2026-24031 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-2026-24031 affect?

CVE-2026-24031 affects dovecot, dovecot. Severity is high (CVSS 7.7). Dovecot SQL based authentication can be bypassed when auth_username_chars is cleared by admin. This vulnerability allows bypassing authentication for any user and user enumeration. Do not clear auth_username_chars. If this is not possible,

How urgent is CVE-2026-24031?

Priority 40/100. High severity; Remotely exploitable, no login, no user action

Software pages

Dovecot vulnerabilities

Related CVEs

CVE-2026-27855 MEDIUM 6.8 UPGRADE UPGRADE Dovecot OTP authentication is vulnerable to replay attack under specific conditions
CVE-2026-27857 MEDIUM 4.3 UPGRADE UPGRADE Sending "NOOP (((...)))" command with 4000 parenthesis open+close results in ~1MB extra memory usage
CVE-2026-27858 HIGH 7.5 UPGRADE UPGRADE Attacker can send a specifically crafted message before authentication that causes managesieve to allocate lar
CVE-2026-27856 HIGH 7.4 UPGRADE UPGRADE Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack
CVE-2026-0394 MEDIUM 5.3 UPGRADE UPGRADE When dovecot has been configured to use per-domain passwd files, and they are placed one path component above

References

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