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

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MEDIUM

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

Published May 23, 2011

6.8

MEDIUM

CVSS 2.0

EPSS 5.16%

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.

Affected products

Remediation

No remediation recorded yet.

Metrics

5.16% 0.05156

Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.

EPSS probability 0.05156

Score over time

2022–2026

EPSS v2
EPSS v3
EPSS v4
EPSS v5

Percentile over time

EPSS v2
EPSS v3
EPSS v4
EPSS v5

Table of values (13 key points)

Flat stretches are collapsed; showing up to 120 newest points.

Date	Score	Percentile	Model
Oct 1, 2026	5.16% (0.05156)	92.17th	v5 (v2026.06.15)
Jun 15, 2026	5.16% (0.05156)	91.32th	v5 (v2026.06.15)
Jun 27, 2025	7.17% (0.07173)	91.10th	v4 (v2025.03.14)
Apr 13, 2025	9.54% (0.09536)	92.12th	v4 (v2025.03.14)
Mar 30, 2025	11.08% (0.11082)	92.83th	v4 (v2025.03.14)
Mar 29, 2025	19.29% (0.19293)	92.41th	v4 (v2025.03.14)
Mar 17, 2025	11.28% (0.11284)	92.99th	v4 (v2025.03.14)
Dec 12, 2024	0.20% (0.00202)	59.09th	v3 (v2023.03.01)
Jun 14, 2024	0.20% (0.00202)	58.39th	v3 (v2023.03.01)
Mar 7, 2023	0.20% (0.00202)	56.36th	v3 (v2023.03.01)
Mar 6, 2023	2.36% (0.02359)	81.45th	v2 (v2022.01.01)
Apr 1, 2022	2.36% (0.02359)	79.69th	v2 (v2022.01.01)
Feb 4, 2022	2.36% (0.02359)	58.33th	v2 (v2022.01.01)

Weaknesses (1)

CWE-264

References (5)

http://secunia.com/advisories/44753
third-party-advisoryx_refsource_SECUNIA
http://www.kb.cert.org/vuls/id/555316
third-party-advisoryx_refsource_CERT-VNUS Government Resource
http://www.kb.cert.org/vuls/id/MAPG-8D9M75
x_refsource_CONFIRMUS Government Resource
http://www.watchguard.com/support/release-notes/xcs/9/en-US/EN_ReleaseNotes_XCS_9_1_1/EN_ReleaseNotes_WG_XCS_9_1_TLS_Hotfix.pdf
x_refsource_CONFIRM
https://exchange.xforce.ibmcloud.com/vulnerabilities/67729
vdb-entryx_refsource_XF

Link	Providers	Tags
http://secunia.com/advisories/44753		third-party-advisoryx_refsource_SECUNIA
http://www.kb.cert.org/vuls/id/555316		third-party-advisoryx_refsource_CERT-VNUS Government Resource
http://www.kb.cert.org/vuls/id/MAPG-8D9M75		x_refsource_CONFIRMUS Government Resource
http://www.watchguard.com/support/release-notes/xcs/9/en-US/EN_ReleaseNotes_XCS_9_1_1/EN_ReleaseNotes_WG_XCS_9_1_TLS_Hotfix.pdf		x_refsource_CONFIRM
https://exchange.xforce.ibmcloud.com/vulnerabilities/67729		vdb-entryx_refsource_XF

Change history (0)

No recorded changes yet.

Sources

CVE.org / MITRE

Status PUBLISHED

Assigner mitre

Published May 23, 2011

Updated Aug 6, 2024

Reserved May 23, 2011

Link CVE-2011-2165

CISA Vulnrichment

Updated n/a

NVD

Status Modified

Modified Jun 16, 2026

Link CVE-2011-2165

Red Hat

Severity n/a

Public date n/a

Links CVE-2011-2165