Security readout for executives and security teams
Plain-English summary
This CVE describes an audit logging gap in JetBrains TeamCity before 2020.2.2. When an administrator uploaded a file, the audit logs were not sufficient. The available sources do not describe direct compromise, data exposure, or active exploitation, but weak logs can hinder incident investigation and accountability.
Executive priority
Prioritize as a governance and incident-response hygiene issue unless your TeamCity server is heavily regulated or under investigation. Upgrade aging TeamCity instances during normal vulnerability remediation cycles, with higher priority where administrator activity must be auditable.
Technical view
The issue affects TeamCity versions before 2020.2.2 and concerns insufficient audit log detail for administrator file uploads. The source bundle does not identify missing fields, file-upload locations, CVSS, CWE, exploitability, or impact beyond audit insufficiency. Treat it as an observability and forensic-control weakness.
Likely exposure
Organizations running JetBrains TeamCity before 2020.2.2 are potentially exposed. Exposure is most relevant where administrators can upload files and audit logs are relied on for change tracking, compliance evidence, or incident reconstruction.
Exploitation context
The provided sources do not show active exploitation, public exploit availability, or CISA KEV listing. The issue requires an administrator upload event, so the known concern is incomplete logging rather than a documented unauthenticated attack path.
Researcher notes
Evidence is sparse. The bundle names TeamCity before 2020.2.2 and states only that administrator file-upload audit logs were insufficient. It does not provide CVSS, CWE, affected CPEs, root cause, exploit mechanics, or detailed patch notes.
Mitigation direction
- Upgrade TeamCity to 2020.2.2 or later if still running an older version.
- Review JetBrains security bulletin guidance for any vendor-specific remediation notes.
- Restrict TeamCity administrator access to trusted, named users only.
- Retain complementary logs from reverse proxies, CI agents, and identity providers.
- Document compensating monitoring where old audit logs cannot prove upload activity.
Validation and detection
- Inventory TeamCity instances and confirm exact version numbers.
- Check whether any instance is older than 2020.2.2.
- Review audit records around administrator file uploads for completeness gaps.
- Confirm administrator accounts are individually assigned and regularly reviewed.
- Verify retention of external logs that can corroborate TeamCity administrative actions.
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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CVE-2021-31906 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://blog.jetbrains.com/CVE reference · x_refsource_MISC
- https://blog.jetbrains.com/blog/2021/05/07/jetbrains-security-bulletin-q1-2021/CVE 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.