CVE-2011-1506

CVE-2011-1506 is a medium-severity vulnerability in Kerio Connect with a CVSS 2.0 base score of 6.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

• Severity: Medium (CVSS 2.0 base score 6.8)
• EPSS exploit prediction: 2% (83rd percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-20
• Affected product: Kerio Connect
• Published: 2011-03-22
• Last modified: 2026-06-16

Description

The STARTTLS implementation in Kerio Connect 7.1.4 build 2985 and MailServer 6.x does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted SMTP sessions by sending a cleartext command that is processed after TLS is in place, related to a "plaintext command injection" attack, a similar issue to CVE-2011-0411. NOTE: some of these details are obtained from third party information.

Frequently asked questions

What is CVE-2011-1506?

The STARTTLS implementation in Kerio Connect 7.1.4 build 2985 and MailServer 6.x does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted SMTP sessions by sending a cleartext command that is processed after TLS is in place, related to a "plaintext command injection" attack, a similar issue to CVE-2011-0411. NOTE: some of these details are obtained from third party information.

How severe is CVE-2011-1506?

CVE-2011-1506 has a CVSS 2.0 base score of 6.8, rated medium severity.

Is CVE-2011-1506 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2011-1506?

CVE-2011-1506 primarily affects Kerio Connect. In total, 57 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2011-1506?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2011-1506 published?

CVE-2011-1506 was published on 2011-03-22 and last updated on 2026-06-16.

References

• http://secunia.com/advisories/43678
• http://www.kb.cert.org/vuls/id/555316
• http://www.kb.cert.org/vuls/id/MAPG-8D9M4P
• http://www.securityfocus.com/bid/46767
• http://www.vupen.com/english/advisories/2011/0610
• https://exchange.xforce.ibmcloud.com/vulnerabilities/65932

Affected products (57)

• cpe:2.3:a:kerio:connect:7.1.4:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.0:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.1:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.1.1:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.6.3:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.6.4:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.6.5:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.7.0:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.7.1:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.7.2:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.7.3:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.7.4:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.7.5:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.7.6:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.7.7:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.7.8:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.7.9:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:5.7.10:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0.0:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0.1:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0.2:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0.3:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0.4:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0.5:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0.6:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0.7:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0.8:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0.9:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.0.10:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.1.1:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.1.2:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.1.3:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.1.3_patch_1:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.1.4:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.2.0:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.2.2:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.3.0:*:*:*:*:*:*:*
• cpe:2.3:a:kerio:kerio_mailserver:6.3.1:*:*:*:*:*:*:*

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