Security readout for executives and security teams
Plain-English summary
CVE-2021-33611 is a reflected XSS issue in Vaadin 14 menu-bar webjar resources. An attacker could trick a user into opening a crafted URL and run JavaScript in that user’s browser. Business impact is limited but real: stolen session context or page manipulation may be possible where affected resources are exposed.
Executive priority
Treat as a scheduled remediation item, with higher priority for internet-facing Vaadin applications. The issue needs user interaction and has no cited active exploitation, but browser-session impact can matter in customer or admin portals.
Technical view
The issue is CWE-79 from missing output sanitization in test sources for org.webjars.bowergithub.vaadin:vaadin-menu-bar 1.0.0 through 1.2.0, corresponding to Vaadin 14.0.0 through 14.4.4. CVSS 3.1 is 6.1: network reachable, low complexity, no privileges, user interaction required, changed scope, low confidentiality and integrity impact.
Likely exposure
Exposure is most likely in applications using Vaadin 14.0.0 through 14.4.4 or vaadin-menu-bar 1.0.0 through 1.2.0, especially where the relevant webjar resources are reachable by users.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. Exploitation requires user interaction: a victim must open a crafted URL. The result is reflected JavaScript execution in the browser, not direct server compromise.
Researcher notes
The vulnerability is specifically described as missing sanitization in test sources bundled as webjar resources. Keep analysis scoped to the cited Vaadin and vaadin-menu-bar ranges. The source bundle does not provide exploit telemetry or detailed patch mechanics beyond the vendor advisory and pull request references.
Mitigation direction
- Check Vaadin’s advisory for the vendor-recommended fixed version or upgrade path.
- Identify and update affected vaadin-menu-bar webjar dependencies.
- Prioritize applications exposing Vaadin webjar resources to untrusted users.
- Use existing browser security controls such as CSP as defense-in-depth.
- Monitor Vaadin guidance for any additional mitigation details.
Validation and detection
- Inventory Vaadin framework versions across deployed applications.
- Inspect dependency manifests for org.webjars.bowergithub.vaadin:vaadin-menu-bar 1.0.0 through 1.2.0.
- Confirm whether applications run Vaadin 14.0.0 through 14.4.4.
- Verify affected webjar resources are no longer present after remediation.
- Review security testing for reflected XSS coverage on public routes.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-33611 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
- 6.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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:R/S:C/C:L/I:L/A:N2.82.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.1MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://vaadin.com/security/cve-2021-33611CVE reference · x_refsource_CONFIRM
- https://github.com/vaadin/vaadin-menu-bar/pull/126CVE 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.
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.