Public proof of conceptFix available

CVE-2021-20717

Q: Is CVE-2021-20717 actively exploited?

Active exploitation of CVE-2021-20717 has not been confirmed. Its EPSS score was 2.3% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-20717?

CVE-2021-20717 has a CVSS v3 base score of 6.1 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

A public proof of concept exists; no exploitation attested.

Published2021-05-10
WeaknessCWE-79

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Cross-site scripting vulnerability in EC-CUBE 4.0.0 to 4.0.5 allows a remote attacker to inject a specially crafted script in the specific input field of the EC web site which is created using EC-CUBE. As a result, it may lead to an arbitrary script execution on the administrator's web browser.

Timeline

dates in UTC

2021-05-1010:15CVE publishedNVD
2026-10-2319:23First public proof of conceptPoC-in-GitHub

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-20717?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-20717?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV · NVD

ec-cube/ec-cube

Branch	Affected	Fixed in	Source
4.0	≥ 4.0.0, ≤ 4.0.5	no fix published	OSV

Ec-cube

Branch	Affected	Fixed in	Source
4.0	≥ 4.0.0, < 4.0.5	4.0.5	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

www.ec-cube.netPatch · Vendor Advisory
www.ec-cube.netPatch · Vendor Advisory

Detection

read 2026-10-23 19:23 UTC

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: 1 repository, unverifieds-index/CVE-2021-20717

Sources

NVDCVSS 3.16.1read 2026-10-23
NVDCVSS 2.04.3read 2026-10-23
NVDweakness (CWE)CWE-79read 2026-10-23
FIRST EPSSEPSS score2.3 %2026-10-23
PoC-in-GitHubproof of concept1read 2026-10-23
OSVaffected packages—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Published: 2021-05-10
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-20717?

Is CVE-2021-20717 actively exploited?

Active exploitation of CVE-2021-20717 has not been confirmed. Its EPSS score was 2.3% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-20717?

CVE-2021-20717 has a CVSS v3 base score of 6.1 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

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