Security readout for executives and security teams
Plain-English summary
A local user on a build host could tamper with Vaadin frontend build resources because affected versions used a temporary directory insecurely. The risk is mainly to organizations where untrusted or weakly separated users can access CI, developer, or shared build machines.
Executive priority
Treat as a medium-priority build-chain integrity issue. Prioritize remediation for production build pipelines, shared developer hosts, and CI systems where local user separation is weak.
Technical view
CVE-2021-31411 affects Vaadin frontend build functionality in com.vaadin:flow-server 2.0.9-2.5.2, 3.0 before 6.0, and 6.0.0-6.0.5. It is CWE-379 and can let a low-privileged local user inject malicious code into frontend resources during application rebuilds.
Likely exposure
Exposure is most likely in Vaadin applications built with affected flow-server or Vaadin 14.0.3-14.5.2, Vaadin 15 before 19, or Vaadin 19.0.0-19.0.4 on shared or multi-user build systems.
Exploitation context
The CVSS vector is local, high complexity, and low privilege. The provided sources do not show active exploitation, and the CVE is not listed as KEV. Practical risk depends on local access to the build environment and rebuild timing.
Researcher notes
The vulnerability is constrained by local access and high attack complexity but has high confidentiality and integrity impact if successful. The source bundle does not provide exploit details, observed exploitation, or complete environmental prerequisites beyond local code injection during rebuilds.
Mitigation direction
- Upgrade Vaadin or flow-server to versions outside the affected ranges.
- Confirm the target fixed version against Vaadin's advisory.
- Restrict build host and CI access to trusted users only.
- Rebuild frontend artifacts from a trusted, clean workspace.
- Review vendor guidance before relying on temporary operational workarounds.
Validation and detection
- Inventory Vaadin and com.vaadin:flow-server versions in application dependencies.
- Check whether builds run on shared or multi-user systems.
- Review CI and developer hosts for untrusted local user access.
- Confirm generated frontend resources are rebuilt after upgrading.
- Track remediation evidence against the Vaadin advisory and dependency manifests.
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-379: 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-2021-31411 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:L/UI:N/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:L/UI:N/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:L/UI:N/S:U/C:H/I:H/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://vaadin.com/security/cve-2021-31411CVE reference · x_refsource_CONFIRM
- https://github.com/vaadin/flow/pull/10640CVE 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.
Creation of Temporary File in Directory with Insecure Permissions
Creation of Temporary File in Directory with Insecure Permissions represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.