EUVD-2026-48251
GHSA-8m5q-x899-528f
Severity by source
AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Supplying Kotlin DSL realistically requires VCS-write or project-edit rights, so PR:L rather than PR:N; sandbox escape crosses a trust boundary (S:C) with total host impact (C/I/A:H).
Primary rating from Vendor (JetBrains).
CVSS VectorNVD
Lifecycle Timeline
7DescriptionNVD
In JetBrains TeamCity before 2026.1.2, 2025.11.6 сode execution via Kotlin DSL sandbox escape was possible
AnalysisAI
Remote code execution in JetBrains TeamCity before 2026.1.2 and 2025.11.6 allows an attacker to escape the Kotlin DSL sandbox used to define build configurations-as-code and run arbitrary code in the context of the CI server. Because TeamCity servers hold VCS credentials, deployment keys, and build artifacts, a successful escape effectively compromises the entire build pipeline and downstream software supply chain. There is no public exploit identified at time of analysis, and the flaw is not listed in CISA KEV; EPSS is low at 0.40% (33rd percentile).
Technical ContextAI
TeamCity supports defining project and build settings 'as code' using a Kotlin-based DSL (Kotlin DSL), which is compiled and evaluated by the server. To contain the arbitrary Kotlin code this feature accepts, TeamCity evaluates it inside a restricted sandbox. This vulnerability is a CWE-94 (Improper Control of Generation of Code / code injection) issue where crafted DSL content bypasses the sandbox's restrictions, allowing the supplied Kotlin to execute outside its intended confinement on the server JVM. The affected component is the TeamCity server itself (CPE cpe:2.3:a:jetbrains:teamcity:*), specifically the settings/DSL evaluation subsystem rather than build agents.
RemediationAI
Vendor-released patch: upgrade to TeamCity 2026.1.2 (2026.1.x branch) or 2025.11.6 (2025.11.x maintenance branch), whichever matches your current major line, per JetBrains at https://www.jetbrains.com/privacy-security/issues-fixed/. Until you can upgrade, reduce exposure by restricting who can author or import Kotlin DSL settings: limit project-settings edit and 'versioned settings' write permissions to trusted administrators, and tighten write access on the VCS repositories that back TeamCity settings so untrusted commits cannot introduce DSL. Additionally, keep the TeamCity web UI and API off the public internet (place it behind a VPN or IP allowlist), which limits reachability if the unauthenticated vector is confirmed; the trade-off is reduced convenience for remote developers and integrations. These are compensating controls only - apply the patch as the definitive fix, since disabling versioned settings entirely would break teams that rely on configuration-as-code.
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Same weakness CWE-94 – Code Injection
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External POC / Exploit Code
Leaving vuln.today