Description

In JetBrains CLion before 2026.2, 2026.1.4 code execution was possible in Safe Mode via Meson project settings

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.6",
  "pubDate": "2026-11-06T17:17:21.240Z",
  "pubdate": "2026-11-06T17:17:21.240Z",
  "executiveSummary": "A remote code execution (RCE) vulnerability exists in JetBrains CLion versions prior to 2026.2 and 2026.1.4, specifically involving the processing of Meson project configurations.\nThe vulnerability occurs because CLion's 'Safe Mode'—designed to sandbox or restrict the execution of untrusted project files—fails to adequately sanitize Meson project settings.\nThis flaw allows a local attacker to execute arbitrary code within the context of the CLion application process by providing a malicious Meson build configuration file.\nThe impact is critical, as successful exploitation results in full code execution under the privileges of the user running the IDE. This bypasses the security guarantees intended by Safe Mode, which is meant to prevent the automatic execution of build scripts and project configurations in suspicious or untrusted environments.\nThe risk is high for developers who interact with third-party or externally sourced C++ projects, as merely opening a malformed project folder can lead to compromise.",
  "technicalDetails": "The vulnerability resides within the JetBrains CLion project configuration parser, specifically the component responsible for integrating and interpreting Meson build system files.\nThe root cause is an improper validation and sanitization of user-controlled Meson project settings that are processed during the project loading phase, even when the IDE is operating in 'Safe Mode'.\nIn standard operation, Safe Mode is intended to act as a security boundary, preventing the IDE from executing arbitrary code found in build scripts or build configurations. However, the Meson integration fails to honor these restrictions, allowing the project settings to influence the build environment or internal command execution flows.\nThe attack flow proceeds as follows: An attacker creates a malicious Meson configuration file (e.g., meson.build or related configuration files) designed to trigger unintended code execution. When a victim opens this project in CLion, the IDE's Meson integration logic parses these files to reconstruct the project structure. During this parsing phase, the vulnerable code component fails to enforce the isolation required by Safe Mode.\nThe malicious payload, injected through specific Meson settings, is subsequently passed to system interfaces or internal command executors used by the IDE. This leads to the execution of arbitrary commands or scripts embedded within the Meson configuration.\nBecause this process happens during project indexing and loading, the exploitation does not require the user to manually trigger a build process. The mere act of importing or opening the project directory into CLion is sufficient to trigger the malicious payload.\nThe attack is performed locally; however, the impact is comprehensive. By achieving arbitrary code execution, an attacker gains the ability to modify, delete, or steal files within the user's filesystem, install persistent backdoors, or interact with sensitive credentials stored within the IDE or the user's development environment.\nNo authentication or specific privileges are required beyond the ability to place or convince a victim to open a malicious project folder within CLion. The vulnerability bypasses the intended defensive posture of Safe Mode, rendering that security feature ineffective against specially crafted Meson configurations."
}