Security readout for executives and security teams
Plain-English summary
CVE-2021-31913 affects JetBrains TeamCity before 2020.2.3. During GitHub SSO, TeamCity did not sufficiently validate the redirect_uri used in token exchange. For executives, this is an authentication-flow weakness in a CI/CD system, but the source bundle provides no CVSS score, CWE, exploit detail, or evidence of active exploitation.
Executive priority
Treat as a targeted CI/CD authentication issue requiring inventory and upgrade validation, especially for GitHub SSO deployments. Business urgency depends on exposure and SSO use because the public bundle lacks severity scoring and exploit evidence.
Technical view
The issue is an insufficient redirect_uri check during GitHub SSO token exchange in JetBrains TeamCity versions before 2020.2.3. The provided sources do not describe the exact bypass condition, impact scope, privilege outcome, or exploit prerequisites beyond GitHub SSO involvement.
Likely exposure
Likely exposure is limited to TeamCity deployments earlier than 2020.2.3 using GitHub SSO. Risk is greater where TeamCity authentication endpoints are reachable from the internet or broad internal networks. The bundle does not identify affected editions, CPEs, or impact on other SSO providers.
Exploitation context
The CVE is not listed as KEV in the provided bundle, and no cited source states active exploitation. Public evidence supplied here is limited to the CVE description and JetBrains security bulletin references, so exploitation likelihood cannot be reliably assessed from this bundle alone.
Researcher notes
The available evidence is sparse. The useful pivot points are TeamCity before 2020.2.3, GitHub SSO token exchange, and redirect_uri validation. Avoid assuming account takeover or token theft without JetBrains advisory detail or additional primary-source evidence.
Mitigation direction
- Identify all JetBrains TeamCity servers and their exact versions.
- Upgrade TeamCity instances earlier than 2020.2.3 to 2020.2.3 or later.
- Prioritize systems using GitHub SSO for remediation.
- Restrict TeamCity login exposure where business requirements allow.
- Review JetBrains guidance for any additional SSO configuration recommendations.
Validation and detection
- Check TeamCity version inventory for any instance earlier than 2020.2.3.
- Confirm whether GitHub SSO is enabled on each TeamCity server.
- Map whether TeamCity login endpoints are internet-facing or broadly reachable.
- Review authentication logs for unusual GitHub SSO token exchange or callback activity.
- Record findings and remediation status for vulnerability management tracking.
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.
Credential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-31913 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.