CVE-2020-11806: In MailStore Outlook Add-in (and Email Archive Outlook Add-in) through 12.1.2, the login process does not vali

Q: How do I fix CVE-2020-11806?

mailstore server: upgrade to newer than 12.1.2. Exact commands for each OS are on this page.

Q: Is CVE-2020-11806 being exploited?

CVE-2020-11806 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-2020-11806 affect?

CVE-2020-11806 affects mailstore server. Severity is medium (CVSS 5.9). In MailStore Outlook Add-in (and Email Archive Outlook Add-in) through 12.1.2, the login process does not validate the validity of the certificate presented by the server.

Q: How urgent is CVE-2020-11806?

Priority 36/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.9REMOTEUPGRADE

CVE-2020-11806 is a medium-severity flaw (CVSS 5.9) affecting mailstore server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In MailStore Outlook Add-in (and Email Archive Outlook Add-in) through 12.1.2, the login process does not validate the validity of the certificate presented by the server.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-295
Published	2020-04-23
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: mailstore

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

Am I affected?

Timeline

2020-04-23 15:15 UTCPublished CVE record published
2026-06-17 02:50 UTCUpdated Record last modified

mailstore mailstore server UPGRADE

Affected: <= 12.1.2

Fixed in: newer than 12.1.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy mailstore-server || rpm -q mailstore-server || mailstore-server --version

2. UPGRADE to newer than 12.1.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade mailstore-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mailstore-server

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-2020-11806?

mailstore server: upgrade to newer than 12.1.2. Exact commands for each OS are on this page.

Is CVE-2020-11806 being exploited?

CVE-2020-11806 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-2020-11806 affect?

CVE-2020-11806 affects mailstore server. Severity is medium (CVSS 5.9). In MailStore Outlook Add-in (and Email Archive Outlook Add-in) through 12.1.2, the login process does not validate the validity of the certificate presented by the server.

How urgent is CVE-2020-11806?

Priority 36/100. Remotely exploitable, no login, no user action

Software pages

Outlook vulnerabilities

Related CVEs

CVE-2019-10229 HIGH 8.8 UPGRADE UPGRADE An issue was discovered in MailStore Server (and Service Provider Edition) 9.x through 11.x before 11.2.2

References

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