HOMEVULNERABILITIESCVE-2020-36321
HIGH

CVE-2020-36321

CWE-22Published: April 23, 2021· Updated: Jun 17, 2026

7.5
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2020-36321 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityNone
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected Vendors & Products

vaadin2 product(s)
flowvaadin
Source: NVD CPE · 2 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/vaadin/flow/pull/9392
PATCHhttps://github.com/vaadin/flow/pull/9392
ADVISORYhttps://vaadin.com/security/cve-2020-36321
ADVISORYhttps://vaadin.com/security/cve-2020-36321

All References (4)

→
https://github.com/vaadin/flow/pull/9392Patch · Third Party Advisory
→
https://vaadin.com/security/cve-2020-36321Vendor Advisory
→
https://github.com/vaadin/flow/pull/9392Patch · Third Party Advisory
→
https://vaadin.com/security/cve-2020-36321Vendor Advisory

Quick Facts

CVE IDCVE-2020-36321
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-22
CISA KEVNo
Affected1 vendor(s)
PublishedApr 23, 2021

Related CVEs (CWE-22)

CVE-2026-54917
10.0
CVE-2006-5487
10.0
CVE-2025-64075
10.0
CVE-2026-39861
10.0
CVE-2026-11429
10.0
CVE-2007-5364
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2020-36321 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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