Security readout for executives and security teams
Plain-English summary
This Vaadin flaw can let an unauthenticated network user discover application routes when a vulnerable app runs in production mode with Vaadin’s default not-found handling. It is information disclosure, not direct code execution, but exposed route maps can help attackers plan follow-on probing.
Executive priority
Treat this as a moderate-priority exposure-reduction item. It is unlikely to be business-critical alone, but it can expose application structure to unauthenticated users and should be fixed during the next normal security maintenance cycle, sooner for public apps.
Technical view
CVE-2021-31412 is improper path sanitization in Vaadin Flow Server’s default RouteNotFoundError view. A crafted HTTP request may reveal available routes if no custom NotFoundException handler is configured. Affected ranges include Vaadin 10, 11-14, and 15-19 mapped to flow-server 1.x, 2.x, 3.x-6.0.9 as specified by the CVE.
Likely exposure
Internet-facing Vaadin applications are the main concern if they use affected Flow Server versions, run in production mode, and rely on the default not-found route handler.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. The CVSS vector indicates remote, unauthenticated, low-complexity information disclosure with low confidentiality impact only.
Researcher notes
Validation should focus on version range matching and configuration prerequisites. The issue is conditional: vulnerable version, production mode, and default not-found handling. Avoid treating every Vaadin deployment as exposed without confirming those conditions.
Mitigation direction
- Identify Vaadin and com.vaadin:flow-server versions in deployed applications.
- Upgrade to a Vaadin or Flow Server release outside the affected ranges.
- Check Vaadin’s advisory for exact fixed versions and supported upgrade paths.
- Configure a custom NotFoundException handler if vendor guidance recommends it.
- Prioritize internet-facing production Vaadin applications first.
Validation and detection
- Inventory applications using Vaadin 10, 11-14, or 15-19.
- Review dependency manifests for affected com.vaadin:flow-server versions.
- Confirm whether production mode is enabled on deployed systems.
- Check whether a custom NotFoundException handler replaces the default view.
- After remediation, verify dependency versions are outside listed vulnerable ranges.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CWE-1295: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-31412 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N3.91.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://vaadin.com/security/cve-2021-31412CVE reference · x_refsource_CONFIRM
- https://github.com/vaadin/flow/pull/11107CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Debug Messages Revealing Unnecessary Information
Debug Messages Revealing Unnecessary Information represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.