CVE-2021-33604 json
Reflected cross-site scripting in development mode handler in Vaadin 14, 15-19
published 2021-06-24 5 y ago modified 2026-06-17 4 mo ago also GHSA-c99r-67x4-whj6 , EUVD-2021-1309
- cvss
- 2.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 21%
- public exploits
- 0
- none known
Summary
URL encoding error in development mode handler in com.vaadin:flow-server versions 2.0.0 through 2.6.1 (Vaadin 14.0.0 through 14.6.1), 3.0.0 through 6.0.9 (Vaadin 15.0.0 through 19.0.8) allows local user to execute arbitrary JavaScript code by opening crafted URL in browser.
Patch / fix
Exploit prediction
0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 2.5 | CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N |
| NVD | 3.1 | 2.5 | CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N |
| NVD | 2.0 | 1.2 | AV:L/AC:H/Au:N/C:P/I:N/A:N |
| GitHub | 3.1 | 2.5 | CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| maven | com.vaadin:vaadin-bom | >=14.0.0, <14.6.2 >=15.0.0, <19.0.9 |
14.6.2 19.0.9 |
Affected products
- Vaadin Vaadin
- Vaadin flow-server
Classification
- Weakness
-
- CWE-172 Improper Encoding or Decoding of Data
References
-
github.com
/vaadin/flow/pull/11099
web, patch, third-party-advisory
-
vaadin.com
/security/cve-2021-33604
web, vendor-advisory
-
github.com
/vaadin/platform/security/advisories/GHSA-c99r-67x4-whj6
web
-
nvd.nist.gov
/vuln/detail/CVE-2021-33604
advisory
-
github.com
/vaadin/flow
web
Sources
- CVE List CVE-2021-33604
- GitHub Advisory GHSA-c99r-67x4-whj6
- NVD CVE-2021-33604
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.