Reflected cross-site scripting in development mode handler in Vaadin 14, 15-19
Noroxi assessment
Priority: Monitor (action score 10/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.28% (FIRST EPSS).
- Someone with local access to the system can trigger it. No account or password is required. A user must open a link or visit a page. Special conditions such as timing or configuration are required.
- Fixed version: com.vaadin:vaadin-bom (Maven) 14.6.2, 19.0.9.
Low priority for now. Upgrade to com.vaadin:vaadin-bom (Maven) 14.6.2, 19.0.9 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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.
- Published
- Jun 24, 2021
- Updated
- Jun 16, 2026
- EPSS
- 0.2% · 20th percentile
- CWE
- CWE-172
Report tools
Action score
10
Monitor
Low priority for now.
- CVSS
- 10 / 40 · 2.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
CNA vs NVD score
- NVD
- 2.5
- CNA · Vaadin
- 2.5
- agree
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- vaadin flow-server2.0.0 and later · up to 2.6.1 inclusive
- vaadin flow-server3.0.0 and later · up to 5.0.0 inclusive
- vaadin flow-server6.0.0 and later · up to 6.0.9 inclusive
- vaadin vaadin14.0.0 and later · up to 14.6.1 inclusive
- vaadin vaadin15.0.0 and later · up to 18.0.0 inclusive
- vaadin vaadin19.0.0 and later · up to 19.0.8 inclusive
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Vaadin). Independent of NVD's CPE analysis and usually ahead of it.
Vaadin flow-server
- 2.0.0 and later · before unspecifiedaffected
- unspecified and later · up to and including 2.6.1affected
- 3.0.0 and later · before unspecifiedaffected
- unspecified and later · up to and including 6.0.9affected
Vaadin Vaadin
- 14.0.0 and later · before unspecifiedaffected
- unspecified and later · up to and including 14.6.1affected
- 15.0.0 and later · before unspecifiedaffected
- unspecified and later · up to and including 19.0.8affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Maven | com.vaadin:vaadin-bom | from 14.0.0 · before 14.6.2 | 14.6.2 |
| Maven | com.vaadin:vaadin-bom | from 15.0.0 · before 19.0.9 | 19.0.9 |
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Maven:com.vaadin:vaadin-bom | 14.6.2 | Package registry (OSV) |
| Maven:com.vaadin:vaadin-bom | 19.0.9 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- No account or password is required.
- A user must open a link or visit a page.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- low · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Local
- Attack complexity
- High
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality impact
- Low
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-172 · Encoding ErrorCVSS vector
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Double EncodingCAPEC-120likelihood: Low · Medium
- Leverage Alternate EncodingCAPEC-267likelihood: High · High
- Using Leading 'Ghost' Character Sequences to Bypass Input FiltersCAPEC-3likelihood: Medium · Medium
- Embedding NULL BytesCAPEC-52likelihood: High · High
- Postfix, Null Terminate, and BackslashCAPEC-53likelihood: High · High
- Using Slashes and URL Encoding Combined to Bypass Validation LogicCAPEC-64likelihood: High · High
- Using Unicode Encoding to Bypass Validation LogicCAPEC-71likelihood: Medium · High
- URL EncodingCAPEC-72likelihood: High · High
ATT&CK techniques
Change log
- Fix✗ → ✓
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References
Show all references (1 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.