EUVD-2026-42913
GHSA-ch3x-q6cp-54rw
Severity by source
AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Unauthenticated network injection (PR:N/AV:N) but fires only when a victim views the page (UI:R); stored XSS executes in the victim's browser context, so S:C with limited C/I and no availability impact.
Primary rating from Vendor (JetBrains).
CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Lifecycle Timeline
5DescriptionNVD
In JetBrains TeamCity before 2026.1.2 stored XSS via unauthenticated agent registration was possible
AnalysisAI
Stored cross-site scripting in JetBrains TeamCity before 2026.1.2 lets an unauthenticated attacker persist malicious script through the agent registration flow, which then executes in the browser of any privileged user (e.g. an administrator) who later views the affected agent-management interface. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that the TeamCity server's agent registration is reachable by the attacker and accepts registrations without authentication (PR:N), which is the default agent-connection model; the attacker injects the stored payload during that registration. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 base score is 8.1 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N), reflecting network reachability, low complexity, and no privileges required, offset only by required user interaction (a privileged user must view the poisoned content). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker with only network access to the TeamCity server registers a malicious build agent, embedding a JavaScript payload in an agent-controlled field that is stored by the server. When an administrator later opens the agent list or agent details page, the payload executes in their authenticated session, allowing the attacker to steal session cookies/CSRF tokens or issue actions as that admin - potentially leading to takeover of the CI/CD pipeline. … |
| Remediation | Vendor-released patch: 2026.1.2 - upgrade the TeamCity server to 2026.1.2 or later, which is the primary and authoritative fix; consult the JetBrains security bulletin at https://www.jetbrains.com/privacy-security/issues-fixed/ for release specifics. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Identify all TeamCity instances and versions < 2026.1.2; review agent registration logs for suspicious activity and preserve for investigation. …
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Same weakness CWE-79 – Cross-site Scripting (XSS)
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External POC / Exploit Code
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