CVE-2021-27899

The Proofpoint Insider Threat Management Agents (formerly ObserveIT Agent) for MacOS and Linux perform improper validation of the ITM Server's certificate, which enables a remote attacker to intercept and alter these communications using a man-in-the-middle attack. All versions before 7.11.1 are affected. Agents for Windows and Cloud are not affected.

Published: 2021-04-06 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-27899 is rated Moderate Risk (46.1/100): CVSS High severity, with low exploitation likelihood (EPSS 0.64%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-27899

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.11% 0.64% +0.53%
2 2025-03-30 0.15% 0.11% -0.05%
3 2025-03-29 — 0.15% —

Full EPSS history (11 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-27899

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.4 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 5.2 [email protected]
5.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 4.9 [email protected]

Weakness enumeration for CVE-2021-27899

Affected software / configurations for CVE-2021-27899

Vendor Product Version Raw CPE
proofpoint insider_threat_management >= 7.9.0, < 7.9.3 cpe:2.3:a:proofpoint:insider_threat_management:*:*:*:*:*:linux:*:*
proofpoint insider_threat_management >= 7.10.0, < 7.10.3 cpe:2.3:a:proofpoint:insider_threat_management:*:*:*:*:*:linux:*:*
proofpoint insider_threat_management >= 7.11.0, < 7.11.1 cpe:2.3:a:proofpoint:insider_threat_management:*:*:*:*:*:linux:*:*
proofpoint insider_threat_management >= 7.9.0, < 7.9.3 cpe:2.3:a:proofpoint:insider_threat_management:*:*:*:*:*:macos:*:*
proofpoint insider_threat_management >= 7.10.0, < 7.10.3 cpe:2.3:a:proofpoint:insider_threat_management:*:*:*:*:*:macos:*:*
proofpoint insider_threat_management >= 7.11.0, < 7.11.1 cpe:2.3:a:proofpoint:insider_threat_management:*:*:*:*:*:macos:*:*

References for CVE-2021-27899

cvelogic Threat Intelligence