Security readout for executives and security teams
Plain-English summary
Vaadin applications using the affected Authentication.logout() helper may not actually end a user’s server session. After a user attempts to log out, access to Fusion endpoints can remain possible in specific Spring Security CSRF configurations.
Executive priority
Treat this as a targeted remediation item for Vaadin-based applications, not an internet-wide emergency. Prioritize systems handling sensitive user data or administrative Fusion endpoints.
Technical view
CVE-2021-31408 is CWE-613 session expiration weakness in com.vaadin:flow-client. The logout helper used an incorrect HTTP method, interacting poorly with Spring Security CSRF protection and leaving the server session valid after logout attempts.
Likely exposure
Exposure is limited to Vaadin 18 and Vaadin 19 applications using affected flow-client versions and the Authentication.logout() helper with Spring Security CSRF protection.
Exploitation context
The CVSS vector is local, high complexity, no privileges, and requires user interaction. The source bundle does not show CISA KEV listing or confirmed active exploitation.
Researcher notes
Evidence supports a session invalidation failure tied to incorrect HTTP method use and Spring Security CSRF behavior. Sources do not provide proof of exploitation in the wild.
Mitigation direction
- Upgrade Vaadin or flow-client to versions outside the affected ranges named by Vaadin.
- Check Vaadin’s CVE advisory and project dependency lockfiles before changing versions.
- Review logout implementation if Authentication.logout() is used with Spring Security CSRF protection.
- Confirm server-side session invalidation occurs after user logout.
Validation and detection
- Inventory Vaadin and com.vaadin:flow-client versions in application dependencies.
- Identify whether Vaadin Fusion endpoints are exposed in affected applications.
- Verify whether Authentication.logout() is used for application logout behavior.
- Test logout behavior defensively to confirm the server session is invalidated.
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
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-613: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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-2021-31408 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
- 6.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/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:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N15.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.3MediumVector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://vaadin.com/security/cve-2021-31408CVE reference · x_refsource_MISC
- https://github.com/vaadin/flow/pull/10577CVE reference · x_refsource_MISC
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.
Insufficient Session Expiration
Insufficient Session Expiration represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.