CVE-2021-31404
Timing side channel vulnerability in UIDL request handler in Vaadin 10, 11-14, and 15-18
Non-constant-time comparison of CSRF tokens in UIDL request handler in com.vaadin:flow-server versions 1.0.0 through 1.0.13 (Vaadin 10.0.0 through 10.0.16), 1.1.0 prior to 2.0.0 (Vaadin 11 prior to 14), 2.0.0 through 2.4.6 (Vaadin 14.0.0 through 14.4.6), 3.0.0 prior to 5.0.0 (Vaadin 15 prior to 18), and 5.0.0 through 5.0.2 (Vaadin 18.0.0 through 18.0.5) allows attacker to guess a security token via timing attack.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Timing side channel vulnerability in UIDL request handler in Vaadin 10, 11-14, and 15-18
Non-constant-time comparison of CSRF tokens in UIDL request handler in com.vaadin:flow-server versions 1.0.0 through 1.0.13 (Vaadin 10.0.0 through 10.0.16), 1.1.0 prior to 2.0.0 (Vaadin 11 prior to 14), 2.0.0 through 2.4.6 (Vaadin 14.0.0 through 14.4.6), 3.0.0 prior to 5.0.0 (Vaadin 15 prior to 18), and 5.0.0 through 5.0.2 (Vaadin 18.0.0 through 18.0.5) allows attacker to guess a security token via timing attack.
- Record
CVE-2021-31404- CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N - Weakness
- CWE-208
- Updated
- 2026-11-02
EUVDEUVD-2021-0890
Non-constant-time comparison of CSRF tokens in UIDL request handler in com.vaadin:flow-server versions 1.0.0 through 1.0.13 (Vaadin 10.0.0 through 10.0.16), 1.1.0 prior to 2.0.0 (Vaadin 11 prior to 14), 2.0.0 through 2.4.6 (Vaadin 14.0.0 through 14.4.6), 3.0.0 prior to 5.0.0 (Vaadin 15 prior to 18), and 5.0.0 through 5.0.2 (Vaadin 18.0.0 through 18.0.5) allows attacker to guess a security token via timing attack.
- Record
EUVD-2021-0890- CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-xwg3-qrcg-w9x6
Timing side channel vulnerability in UIDL request handler in Vaadin 10, 11-14, and 15-18
Non-constant-time comparison of CSRF tokens in UIDL request handler in com.vaadin:flow-server versions 1.0.0 through 1.0.13 (Vaadin 10.0.0 through 10.0.16), 1.1.0 prior to 2.0.0 (Vaadin 11 through 13), 2.0.0 through 2.4.6 (Vaadin 14.0.0 through 14.4.6), 3.0.0 prior to 5.0.0 (Vaadin 15 prior to 18), and 5.0.0 through 5.0.2 (Vaadin 18.0.0 through 18.0.5) allows attacker to guess a security token via timing attack.
- Record
GHSA-xwg3-qrcg-w9x6- CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N - Weakness
- CWE-203, CWE-208
- Updated
- 2026-11-02
NVD
Non-constant-time comparison of CSRF tokens in UIDL request handler in com.vaadin:flow-server versions 1.0.0 through 1.0.13 (Vaadin 10.0.0 through 10.0.16), 1.1.0 prior to 2.0.0 (Vaadin 11 prior to 14), 2.0.0 through 2.4.6 (Vaadin 14.0.0 through 14.4.6), 3.0.0 prior to 5.0.0 (Vaadin 15 prior to 18), and 5.0.0 through 5.0.2 (Vaadin 18.0.0 through 18.0.5) allows attacker to guess a security token via timing attack.
- Record
CVE-2021-31404- CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N - CVSS 3.1
- 2.5 Low
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N - CVSS 2.0
- 1.9 Low
AV:L/AC:M/Au:N/C:P/I:N/A:N - Weakness
- CWE-208, CWE-203
- Updated
- 2026-11-02
OSV
Non-constant-time comparison of CSRF tokens in UIDL request handler in com.vaadin:flow-server versions 1.0.0 through 1.0.13 (Vaadin 10.0.0 through 10.0.16), 1.1.0 prior to 2.0.0 (Vaadin 11 prior to 14), 2.0.0 through 2.4.6 (Vaadin 14.0.0 through 14.4.6), 3.0.0 prior to 5.0.0 (Vaadin 15 prior to 18), and 5.0.0 through 5.0.2 (Vaadin 18.0.0 through 18.0.5) allows attacker to guess a security token via timing attack.
- Record
CVE-2021-31404- CVSS 3.1
- 2.5 Low
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
OSVGHSA-xwg3-qrcg-w9x6
Timing side channel vulnerability in UIDL request handler in Vaadin 10, 11-14, and 15-18
Non-constant-time comparison of CSRF tokens in UIDL request handler in com.vaadin:flow-server versions 1.0.0 through 1.0.13 (Vaadin 10.0.0 through 10.0.16), 1.1.0 prior to 2.0.0 (Vaadin 11 through 13), 2.0.0 through 2.4.6 (Vaadin 14.0.0 through 14.4.6), 3.0.0 prior to 5.0.0 (Vaadin 15 prior to 18), and 5.0.0 through 5.0.2 (Vaadin 18.0.0 through 18.0.5) allows attacker to guess a security token via timing attack.
- Record
GHSA-xwg3-qrcg-w9x6- CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N - Weakness
- CWE-203, CWE-208
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
com.vaadin:flow-serverMaven |
1.0.0 up to 1.0.14 | 1.0.14 |
com.vaadin:flow-serverMaven |
1.1.0 up to 2.4.7 | 2.4.7 |
com.vaadin:flow-serverMaven |
3.0.0 up to 5.0.3 | 5.0.3 |
com.vaadin:flow-serverMaven |
1.0.0 up to 1.0.14, plus listed versions 1.0.11.0.101.0.111.0.121.0.13 Show 8 moreShow less1.0.21.0.31.0.41.0.51.0.61.0.71.0.81.0.9 |
1.0.14 |
com.vaadin:flow-serverMaven |
1.1.0 up to 2.4.7, plus listed versions 1.2.01.2.11.2.21.2.31.2.4 Show 45 moreShow less1.2.51.3.01.4.01.4.11.4.21.4.31.4.41.4.51.4.61.4.71.4.82.0.02.0.12.0.102.0.112.0.122.0.132.0.142.0.152.0.162.0.172.0.182.0.192.0.22.0.32.0.42.0.52.0.62.0.72.0.82.0.92.1.02.1.0.beta22.1.12.1.22.1.32.1.42.1.52.1.62.1.72.1.82.1.92.2.02.2.0.alpha112.2.1 |
2.4.7 |
com.vaadin:flow-serverMaven |
3.0.0 up to 5.0.3, plus listed versions 3.0.13.0.23.0.33.0.43.0.5 Show 21 moreShow less3.0.63.0.73.1.03.1.13.1.23.1.33.1.53.1.63.1.74.0.04.0.14.0.24.0.34.0.44.0.54.0.64.0.74.0.85.0.05.0.15.0.2 |
5.0.3 |
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-2021-31404 is a medium vulnerability (CVSS 4.0) 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 0.21%, the 11th percentile. Fixed in com.vaadin:flow-server 1.0.14.
References
Left out here: 18 versions. The JSON record has them.