Security readout for executives and security teams
Plain-English summary
A logged-in attacker could escape TeamCity’s Kotlin DSL sandbox and run code on the server. Successful exploitation could expose build secrets, alter software outputs, or disrupt CI/CD operations. JetBrains identifies TeamCity 2026.1.2 and 2025.11.6 as fixed release points.
Executive priority
Prioritize remediation promptly because TeamCity can hold source code, signing material, deployment credentials, and control over build outputs. Escalate internet-reachable or broadly accessible installations first. Current evidence supports serious potential impact, but not confirmed exploitation in the wild.
Technical view
CVE-2026-65906 is a CWE-94 code-injection issue involving a Kotlin DSL sandbox escape. CVSS 3.1 scores it 8.8: network-accessible, low complexity, low privileges, no user interaction, with high confidentiality, integrity, and availability impact. Exact permission prerequisites are not described in the supplied sources.
Likely exposure
TeamCity deployments on releases earlier than 2026.1.2 or 2025.11.6 may be exposed, depending on their release branch. The supplied version metadata is incomplete, so administrators should confirm applicability against JetBrains guidance. Network reachability and attacker possession of a low-privileged account increase practical risk.
Exploitation context
The CVSS vector indicates exploitation requires network access and low privileges but no user interaction. The supplied sources do not establish public exploit availability, observed attacks, or inclusion in CISA KEV; the bundle explicitly reports KEV as false.
Researcher notes
The public record is sparse. It identifies a Kotlin DSL sandbox escape and code execution but does not document the vulnerable component, authorization boundary, affected-version floor, detection indicators, or exploitation evidence. Treat detailed prerequisites and affected release ranges as unresolved until JetBrains publishes fuller guidance.
Mitigation direction
- Upgrade affected TeamCity installations to 2026.1.2, 2025.11.6, or a later vendor-supported release.
- Confirm the correct fixed release for each deployed TeamCity branch using JetBrains guidance.
- Restrict TeamCity network access and review accounts with permissions related to Kotlin DSL configurations.
- Rotate sensitive build credentials if investigation finds suspicious code execution or configuration changes.
Validation and detection
- Inventory all TeamCity servers and record their exact installed versions and release branches.
- Verify each installation is at 2026.1.2, 2025.11.6, or a later applicable release.
- Review TeamCity access and audit records for unexpected Kotlin DSL or build-configuration activity.
- Investigate unexplained build changes, server-side processes, secret access, or newly created accounts.
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-94: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. 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 lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-65906 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
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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.
SSVC decision data
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:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H2.85.9JetBrainsVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://www.jetbrains.com/privacy-security/issues-fixed/CVE reference, JetBrains
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.
Improper Control of Generation of Code ('Code Injection')
Improper Control of Generation of Code ('Code Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.