CVE-2026-123276 in CLion
Summary
by MITRE • 11/06/2026
In JetBrains CLion before 2026.3, 2026.2.4.1 code execution was possible in Safe Mode via a crafted GDB server debug profile
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Analysis
by VulDB Data Team • 11/06/2026
The vulnerability identified in JetBrains CLion versions prior to 2026.3 and specifically affecting the 2026.2.4.1 release represents a critical security flaw within the integrated development environment's debugging subsystem. This issue stems from an improper validation of user-supplied input when configuring GDB server debug profiles, allowing for arbitrary code execution under specific operational conditions. The core technical deficiency lies in how CLion processes and executes commands defined within these profile configurations without sufficient sanitization or restriction checks against potentially malicious payloads embedded by a threat actor.
Safe Mode is typically designed to restrict certain functionalities that could pose security risks when opening projects from untrusted sources, thereby preventing automatic execution of build scripts or external tools. However, in this instance, the implementation failed to adequately isolate the GDB server configuration handling within these restricted boundaries. An attacker who can influence the creation or modification of a debug profile, such as through social engineering tactics that trick a developer into opening a malicious project file, could inject crafted commands into the GDB server settings. When the debugger is subsequently launched in Safe Mode, the application erroneously processes and executes these injected commands with the privileges of the user running CLion.
The operational impact of this vulnerability is severe due to its potential for remote code execution or local privilege escalation depending on the context in which the IDE operates. Since developers often run their integrated development environments with elevated permissions to access system resources, hardware devices, or network services, successful exploitation could grant an attacker full control over the host machine. This includes the ability to install malware, exfiltrate sensitive source code and credentials stored within the project directory, pivot into internal networks, or establish persistent backdoors for future unauthorized access. The fact that this occurs in Safe Mode is particularly concerning as it undermines a primary defense mechanism intended to protect users from untrusted content.
From an industry standard perspective, this vulnerability aligns with CWE-94 Improper Control of Generation of Code (Code Injection), specifically where user input directly influences code execution without proper validation. It also maps to MITRE ATT&CK techniques related to Command and Scripting Interpreter abuse, such as T1059 which covers various scripting languages used for lateral movement or persistence. The attack vector likely involves Initial Access through a malicious project file followed by Execution via the debugger component, potentially leading to Persistence if the attacker modifies system configurations during the execution phase.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. JetBrains has addressed this issue in version 2026.3 and later releases; therefore, updating CLion to a patched version is the primary and most effective mitigation step for all users. Until an update can be applied, administrators should enforce strict policies regarding the opening of project files from unknown or untrusted sources. Users must exercise extreme caution when configuring debug profiles, ensuring that no external inputs are accepted without rigorous validation. Additionally, running IDEs with least-privilege principles in mind, such as using standard user accounts rather than administrative ones where possible, can limit the blast radius if exploitation occurs. Security teams should also monitor for unusual process creation events originating from CLion processes, particularly those invoking system shells or network connections during debugging sessions, to detect potential active exploits of this flaw.