CVE-2020-36321
Directory traversal in development mode handler in Vaadin 14 and 15-17
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Directory traversal in development mode handler in Vaadin 14 and 15-17
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.
- Record
CVE-2020-36321- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-22
- Updated
- 2026-11-02
EUVDEUVD-2021-0753
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.
- Record
EUVD-2021-0753- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-49r2-73m6-pp8f
Directory traversal in development mode handler in Vaadin 14 and 15-17
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.
- Record
GHSA-49r2-73m6-pp8f- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-20, CWE-22
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2020-36321- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:P/I:N/A:N - Weakness
- CWE-22
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2020-36321- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - Updated
- 2026-11-02
OSVGHSA-49r2-73m6-pp8f
Directory traversal in development mode handler in Vaadin 14 and 15-17
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.
- Record
GHSA-49r2-73m6-pp8f- CVSS 3.1
- 5.9 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - Weakness
- CWE-20, CWE-22
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
com.vaadin:flow-serverMaven |
3.0.0 up to 5.0.0 | 5.0.0 |
com.vaadin:flow-serverMaven |
2.0.0 up to 2.4.2 | 2.4.2 |
com.vaadin:flow-serverMaven |
3.0.0 up to 5.0.0, plus listed versions 3.0.13.0.23.0.33.0.43.0.5 Show 18 moreShow less3.0.63.0.73.1.03.1.13.1.23.1.33.1.53.1.63.1.74.0.04.0.14.0.24.0.34.0.44.0.54.0.64.0.74.0.8 |
5.0.0 |
com.vaadin:flow-serverMaven |
2.0.0 up to 2.4.2, plus listed versions 2.0.12.0.102.0.112.0.122.0.13 Show 41 moreShow less2.0.142.0.152.0.162.0.172.0.182.0.192.0.22.0.32.0.42.0.52.0.62.0.72.0.82.0.92.1.02.1.0.beta22.1.12.1.22.1.32.1.42.1.52.1.62.1.72.1.82.1.92.2.02.2.0.alpha112.2.12.2.22.2.32.3.02.3.0.beta12.3.12.3.22.3.32.3.42.3.52.3.62.3.72.4.02.4.1 |
2.4.2 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, products | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2020-36321 is a medium vulnerability (CVSS 5.9) in Flow Flow-server, published April 19, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.21%, the 68th percentile. Fixed in com.vaadin:flow-server 5.0.0.