CVE-2021-3553Network attack vector

Data exposure via relay SSRF

Published Nov 24, 2021 · Updated Sep 17, 2024

SSRF in Bitdefender Endpoint Security Tools before 6.6.27.390 allows remote attackers to proxy requests through its protection relay. EPPUpdateService processes a remote configuration file and sends relay requests to an arbitrary remote host; Bitdefender has not disclosed the exact validation failure. Exploitation requires user interaction and an endpoint configured with the Relay role, and its documented impact is confidentiality exposure without integrity or availability loss.

CVSS severity5.3
Medium
EPSS probability1.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in Bitdefender Endpoint Security Tools before 6.6.27.390 allows remote attackers to proxy requests through its protection relay. EPPUpdateService processes a remote configuration file and sends relay requests to an arbitrary remote host; Bitdefender has not disclosed the exact validation failure. Exploitation requires user interaction and an endpoint configured with the Relay role, and its documented impact is confidentiality exposure without integrity or availability loss.

The record

CVE
CVE-2021-3553
Published
Nov 24, 2021
Updated
Sep 17, 2024
Vendor
Bitdefender
Product
GravityZone
Classifications
CWE-918, T1090
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <6.24.1-1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Bitdefender · GravityZoneversion=unspecified <6.24.1-1
Bitdefender · Bitdefender Endpoint Security Tools for Linuxversion=unspecified <6.2.21.160
Bitdefender · Bitdefender Endpoint Security Toolsversion=unspecified <6.6.27.390; version=unspecified <7.1.2.33

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5.3BitdefenderCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
5.0NVDAV:N/AC:L/Au:N/C:P/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1090Proxy

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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