CVE-2021-3553 | Server-Side Request Forgery in EPPUpdateService remote config file (VA-9825)

A Server-Side Request Forgery (SSRF) vulnerability in the EPPUpdateService of Bitdefender Endpoint Security Tools allows an attacker to use the Endpoint Protection relay as a proxy for any remote host. This issue affects: Bitdefender Endpoint Security Tools versions prior to 6.6.27.390; versions prior to 7.1.2.33. Bitdefender Unified Endpoint for Linux versions prior to 6.2.21.160. Bitdefender GravityZone versions prior to 6.24.1-1.

Published: 2021-11-24 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-3553 is rated Moderate Risk (45.3/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.28%). 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-2021-3553

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 0.31% 1.28% +0.97%
2 2026-01-25 0.22% 0.31% +0.09%
3 2025-03-30 — 0.22% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3553

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/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:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
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:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.6 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
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:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-3553

Affected software / configurations for CVE-2021-3553

Vendor Product Version Raw CPE
bitdefender endpoint_security_tools < 6.2.21.160 cpe:2.3:a:bitdefender:endpoint_security_tools:*:*:*:*:*:linux:*:*
bitdefender endpoint_security_tools >= 6.6.27.0, < 6.6.27.390 cpe:2.3:a:bitdefender:endpoint_security_tools:*:*:*:*:*:*:*:*
bitdefender endpoint_security_tools >= 7.0.0.00, < 7.1.2.33 cpe:2.3:a:bitdefender:endpoint_security_tools:*:*:*:*:*:*:*:*
bitdefender gravityzone 6.24.1-1 cpe:2.3:a:bitdefender:gravityzone:6.24.1-1:*:*:*:*:*:*:*

References for CVE-2021-3553

cvelogic Threat Intelligence