CVE-2026-59793: 
JetBrains TeamCity Schwachstellenanalyse und -minderung

CVE-2026-59793 is an arbitrary file access vulnerability in JetBrains TeamCity affecting all versions before 2026.1.2. The flaw exists in the Perforce VCS (Version Control System) integration and allows authenticated low-privileged users to access arbitrary files on the TeamCity server over the network. It was published on July 10, 2026, with a patch released in TeamCity 2026.1.2. The vulnerability carries a CVSS v3.1 base score of 8.8 (High) (GitHub Advisory, JetBrains).

The root cause is classified as CWE-73 (External Control of File Name or Path), where user-supplied input is used to influence file system paths without adequate sanitization or restriction. An authenticated attacker with low privileges can craft requests through the Perforce VCS integration to reference arbitrary file paths on the server, bypassing intended access controls. The attack is network-based, requires no user interaction, and has low complexity, making it straightforward to exploit once authenticated. Associated attack patterns include path manipulation techniques such as URL encoding, slash abuse, and alternate encoding to bypass validation logic (CAPEC-64, CAPEC-76, CAPEC-80) (GitHub Advisory).

Successful exploitation allows an authenticated low-privileged attacker to read arbitrary files on the TeamCity server, potentially exposing sensitive configuration files, credentials, build secrets, source code, and internal tokens. The CVSS scoring reflects high impacts across confidentiality, integrity, and availability, indicating that beyond file disclosure, the vulnerability could facilitate further compromise of the CI/CD pipeline and connected systems. Access to build secrets or VCS credentials could enable lateral movement into source code repositories or downstream infrastructure (GitHub Advisory, JetBrains).

1. Reconnaissance: Identify internet-facing or internally accessible JetBrains TeamCity instances running versions prior to 2026.1.2 using network scanning tools or Shodan/Censys queries targeting TeamCity login pages.
2. Authentication: Obtain or use existing low-privileged credentials to authenticate to the TeamCity instance — no elevated permissions are required.
3. Identify Perforce VCS integration: Navigate to or interact with the Perforce VCS integration feature within TeamCity, which is the vulnerable component.
4. Craft malicious file path request: Submit a crafted request through the Perforce VCS integration that includes a manipulated file path (e.g., using path traversal sequences or alternate encodings) pointing to a sensitive file outside the intended directory (e.g., /etc/passwd, TeamCity configuration files, or credential stores).
5. Retrieve arbitrary file contents: The server processes the attacker-controlled path without sufficient validation and returns the contents of the targeted file, enabling data exfiltration of secrets, credentials, or configuration data (GitHub Advisory).

• Network: Unusual or repeated HTTP requests to TeamCity endpoints associated with Perforce VCS integration containing path traversal sequences (e.g., ../, %2e%2e%2f, %252e%252e) in parameters.
• Logs: TeamCity server access logs showing requests to Perforce VCS integration endpoints with anomalous file path values; error log entries related to unexpected file access attempts outside normal project directories.
• File System: Evidence of access to sensitive files (e.g., database.properties, internal/ directory contents, or OS-level files like /etc/passwd) reflected in file access audit logs.
• Process/Behavior: Low-privileged user accounts accessing VCS integration features outside of normal build activity patterns, particularly during off-hours.

JetBrains has released a fix in TeamCity version 2026.1.2; upgrading to this version or later is the primary recommended remediation (JetBrains, GitHub Advisory). As a temporary workaround if immediate patching is not feasible, administrators should restrict or disable the Perforce VCS integration until the patch can be applied. Additionally, limiting TeamCity access to trusted networks and enforcing the principle of least privilege for user accounts can reduce the attack surface.

Coverage of CVE-2026-59793 appeared across multiple security news outlets including GBHackers, CyberSecurityNews, SecurityOnline, and VPNcentral, typically in the context of a broader JetBrains patch release addressing six vulnerabilities across TeamCity, YouTrack, and IntelliJ IDEA. Social media mentions were noted on Bluesky and Mastodon, with community discussion framing the issue as part of JetBrains' routine security advisory cycle. No notable independent researcher commentary or vendor statements beyond the official advisory were identified.