Security readout for executives and security teams
Plain-English summary
JetBrains TeamCity versions before 2020.2.3 had reflected cross-site scripting on several pages. This could let an attacker cause script to run in a user’s browser while interacting with TeamCity. The source bundle does not provide CVSS severity, exploit details, or evidence of active exploitation.
Executive priority
Treat this as a practical web-application risk for CI infrastructure. Patch exposed or sensitive TeamCity instances promptly, but the provided evidence does not support emergency active-exploitation language.
Technical view
CVE-2021-31911 describes reflected XSS affecting several TeamCity pages before version 2020.2.3. The bundle does not identify specific endpoints, payload conditions, CVSS metrics, CWE mapping, or CPEs. Exposure should be assessed by installed TeamCity version and accessibility of the TeamCity web interface.
Likely exposure
Organizations running JetBrains TeamCity before 2020.2.3 are potentially exposed. Risk is higher where the TeamCity UI is reachable by many users, contractors, or the internet.
Exploitation context
The provided sources do not state active exploitation, and KEV status is false. Reflected XSS typically requires a victim interaction path, but the bundle does not document prerequisites or exploit maturity.
Researcher notes
The record is sparse: no CVSS, CWE, endpoint list, exploit status, or CPE data is provided. Analysis should stay anchored to TeamCity before 2020.2.3 and JetBrains’ Q1 2021 bulletin.
Mitigation direction
- Upgrade TeamCity to 2020.2.3 or later.
- Review the JetBrains security bulletin for vendor guidance.
- Restrict TeamCity UI access to trusted networks and users.
- Prioritize admin and build-system user accounts for hardening.
Validation and detection
- Inventory all TeamCity instances and record exact versions.
- Confirm no production instance runs before 2020.2.3.
- Check whether TeamCity is internet-accessible or broadly reachable.
- Review recent TeamCity access patterns for suspicious user-targeting activity.
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.
CVE-2021-31911 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.