CVE-2021-20751

Cross-site scripting vulnerability in EC-CUBE EC-CUBE 4.0.0 to 4.0.5-p1 (EC-CUBE 4 series) allows a remote attacker to inject an arbitrary script by leading an administrator or a user to a specially crafted page and to perform a specific operation.

Published: 2021-06-28 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-20751 is rated Moderate Risk (46.2/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.09%). 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-2021-20751

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 0.59% 1.09% +0.50%
2 2026-02-17 0.32% 0.59% +0.27%
3 2025-03-30 — 0.32% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-20751

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.7 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/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:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2021-20751

GitHub Security Advisory for CVE-2021-20751

GHSA-r6qq-qc9m-98w2 · Severity: medium · Ecosystem: composer — EC-CUBE Cross-site scripting vulnerability

Affected software / configurations for CVE-2021-20751

Vendor Product Version Raw CPE
ec-cube ec-cube >= 4.0.0, < 4.0.5 cpe:2.3:a:ec-cube:ec-cube:*:*:*:*:*:*:*:*
ec-cube ec-cube 4.0.5. cpe:2.3:a:ec-cube:ec-cube:4.0.5.:-:*:*:*:*:*:*

References for CVE-2021-20751

cvelogic Threat Intelligence