How severe is CVE-2011-2165?

CVE-2011-2165 has a CVSS 2.0 base score of 6.8, rated medium severity.

Is CVE-2011-2165 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2011-2165?

CVE-2011-2165 primarily affects Watchguard Xcs. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2011-2165?

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

When was CVE-2011-2165 published?

CVE-2011-2165 was published on 2011-05-23 and last updated on 2026-06-16.

CVE-2011-2165

CVE-2011-2165 is a medium-severity vulnerability in Watchguard Xcs 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-264.

Key facts

Severity: Medium (CVSS 2.0 base score 6.8)
EPSS exploit prediction: 5% (91st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-264
Affected product: Watchguard Xcs
Published: 2011-05-23
Last modified: 2026-06-16

Description

The STARTTLS implementation in WatchGuard XCS 9.0 and 9.1 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.

Frequently asked questions

What is CVE-2011-2165?: The STARTTLS implementation in WatchGuard XCS 9.0 and 9.1 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.
How severe is CVE-2011-2165?: CVE-2011-2165 has a CVSS 2.0 base score of 6.8, rated medium severity.
Is CVE-2011-2165 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2011-2165?: CVE-2011-2165 primarily affects Watchguard Xcs. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2011-2165?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2011-2165 published?: CVE-2011-2165 was published on 2011-05-23 and last updated on 2026-06-16.

References

Affected products (2)

cpe:2.3:a:watchguard:xcs:9.0:*:*:*:*:*:*:*
cpe:2.3:a:watchguard:xcs:9.1:*:*:*:*:*:*:*

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