No exploitation reportedFix available

CVE-2020-36321

Q: Is CVE-2020-36321 actively exploited?

Active exploitation of CVE-2020-36321 has not been confirmed. Its EPSS score was 1.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2020-36321?

CVE-2020-36321 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

No exploitation reported by the sources we read.

Published2021-04-23
Fixed in18.0.0 · 14.4.3
WeaknessCWE-22

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

Improper URL validation in development mode handler in com.vaadin:flow-server versions 2.0.0 through 2.4.1 (Vaadin 14.0.0 through 14.4.2), and 3.0 prior to 5.0 (Vaadin 15 prior to 18) allows attacker to request arbitrary files stored outside of intended frontend resources folder.

Timeline

dates in UTC

2021-04-2316:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 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-2020-36321?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-36321?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Vaadin

Branch	Affected	Fixed in	Source
18.0	≥ 15.0.0, < 18.0.0	18.0.0	NVD
14.x	≥ 14.0.0, < 14.4.3	14.4.3	NVD

Vaadin flow

Branch	Affected	Fixed in	Source
5.0	≥ 3.0.0, < 5.0.0	5.0.0	NVD
2.x	≥ 2.0.0, < 2.4.2	2.4.2	NVD

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

Fix

Update Vaadin to 18.0.0 · 14.4.3

Advisories and patches

github.comPatch
vaadin.comVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CNACVSS 3.15.9read 2026-10-23
NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.05read 2026-10-23
CNAweakness (CWE)CWE-22read 2026-10-23
NVDweakness (CWE)CWE-22read 2026-10-23
FIRST EPSSEPSS score1.2 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Published: 2021-04-23
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2020-36321?

Is CVE-2020-36321 actively exploited?

Active exploitation of CVE-2020-36321 has not been confirmed. Its EPSS score was 1.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-36321?

CVE-2020-36321 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

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