CVE-2023-39059 in Semaphore
Summary
by MITRE • 08/29/2023
An issue in ansible semaphore v.2.8.90 allows a remote attacker to execute arbitrary code via a crafted payload to the extra variables parameter.
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Analysis
by VulDB Data Team • 07/27/2025
The vulnerability identified as CVE-2023-39059 represents a critical remote code execution flaw within the ansible semaphore web application version 2.8.90. This security weakness resides in the application's handling of extra variables parameters, which are commonly used in ansible automation workflows to pass dynamic configuration data to playbooks. The vulnerability stems from insufficient input validation and sanitization mechanisms that fail to properly process user-supplied data before incorporating it into the execution context of ansible tasks. Attackers can exploit this weakness by crafting malicious payloads that leverage the extra variables parameter to inject and execute arbitrary commands on the target system where semaphore is running. This flaw fundamentally undermines the security boundaries of the application and creates an avenue for attackers to gain full control over the automation infrastructure.
The technical implementation of this vulnerability aligns with common software security patterns where parameter injection occurs due to inadequate sanitization of user inputs. The extra variables parameter in ansible semaphore is designed to accept dynamic data that gets processed and passed to ansible playbooks, but the application fails to properly validate or escape special characters that could be interpreted as command sequences. This creates a classic command injection scenario where attacker-controlled data flows directly into system execution contexts without proper isolation or sanitization. The vulnerability operates at the application layer and can be exploited remotely without requiring authentication, making it particularly dangerous in environments where semaphore is exposed to untrusted networks or user populations.
The operational impact of CVE-2023-39059 extends beyond simple privilege escalation to encompass complete system compromise and potential lateral movement within network environments. An attacker who successfully exploits this vulnerability can execute arbitrary code with the privileges of the semaphore service account, which typically has access to sensitive automation infrastructure including access to production systems, configuration management data, and potentially privileged credentials stored within the automation environment. This vulnerability directly maps to attack patterns described in the MITRE ATT&CK framework under the T1059.001 technique for command and script injection, while also aligning with CWE-77 for command injection vulnerabilities. The impact is particularly severe in continuous integration/continuous deployment environments where semaphore is used to orchestrate critical infrastructure automation tasks, as successful exploitation could lead to complete compromise of the entire automation pipeline.
Mitigation strategies for CVE-2023-39059 should prioritize immediate patching of the ansible semaphore application to version 2.8.91 or later, which contains the necessary fixes for the input validation issues. Organizations should implement network segmentation to limit access to semaphore interfaces and restrict exposure to trusted networks only. Additional defensive measures include implementing web application firewalls to monitor and filter suspicious payloads targeting the extra variables parameter, conducting thorough input validation at multiple layers of the application architecture, and establishing strict access controls for semaphore interfaces. Security teams should also consider implementing runtime monitoring to detect anomalous command execution patterns and establish incident response procedures specifically tailored to automation infrastructure compromises. Regular security assessments of automation tools and infrastructure should be conducted to identify similar vulnerabilities across the broader technology stack, as this type of injection vulnerability often indicates broader architectural weaknesses that may affect other components of the automation environment.