CVE-2026-56748 in Stream
Summary
by MITRE • 07/27/2026
Improper validation of symbolic links in the Pack Git import feature in Cribl Stream before 4.18.2 allows a remote authenticated attacker with Pack import and pipeline preview permissions to execute arbitrary code as the Cribl server process via a crafted Git repository containing a symbolic link in the pack's functions directory.
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Analysis
by VulDB Data Team • 07/27/2026
This vulnerability exists within the Pack Git import functionality of Cribl Stream versions prior to 4.18.2, representing a critical security flaw that enables remote code execution through improper symbolic link validation. The issue specifically affects the handling of symbolic links within the pack's functions directory during Git repository imports, creating a pathway for authenticated attackers to escalate privileges and execute arbitrary code with the elevated permissions of the Cribl server process. The vulnerability stems from insufficient input validation mechanisms that fail to properly sanitize or reject malicious symbolic link references during the import process.
The technical exploitation occurs when an attacker crafts a malicious Git repository containing carefully constructed symbolic links within the pack's functions directory structure. When the Cribl Stream system processes this repository through its Pack Git import feature, the system attempts to resolve these symbolic links without proper validation checks, allowing the attacker to reference files outside of the intended scope. This behavior violates fundamental security principles of access control and privilege separation, as the system operates with elevated privileges during the import process while failing to validate the legitimacy of symbolic link targets. The flaw manifests as a path traversal vulnerability that can be leveraged to execute code within the context of the Cribl server process, potentially leading to complete system compromise.
From an operational impact perspective, this vulnerability represents a significant risk to organizations using Cribl Stream, particularly those with distributed teams or external partners who may have access to pack import functionality. Attackers with just basic authentication credentials and pipeline preview permissions can exploit this flaw, making it particularly dangerous in environments where least privilege principles are not strictly enforced. The remote execution capability means that attackers do not need physical access to the system, enabling exploitation from any network location where they can authenticate to the Cribl Stream instance. This vulnerability directly aligns with CWE-22 Path Traversal and CWE-78 Command Injection categories, both of which are classified as high-risk security flaws in the Common Weakness Enumeration catalog.
The attack vector specifically targets the Git import workflow within Cribl Stream's pack management system, where symbolic links in the functions directory are processed without proper validation. This weakness creates a direct pathway for privilege escalation attacks that can be executed by any authenticated user with sufficient permissions to import packs and preview pipelines. The security implications extend beyond simple code execution to include potential data exfiltration, system reconnaissance, and lateral movement within the network environment. Organizations should consider this vulnerability in the context of ATT&CK technique T1059 Command and Scripting Interpreter and T1548 Privilege Escalation frameworks, as it enables both code execution and elevated privilege access through a single attack vector.
Mitigation strategies should focus on immediate patching to Cribl Stream version 4.18.2 or later, which includes proper symbolic link validation mechanisms in the Git import functionality. Organizations should also implement additional security controls such as restricting pack import permissions to minimal necessary users, monitoring Git repository imports for suspicious patterns, and conducting regular security assessments of third-party pack repositories. Network segmentation and access control measures can help limit the potential impact if exploitation occurs, while proper logging and monitoring of pack import activities will aid in detecting unauthorized attempts to exploit this vulnerability. The fix implemented by Cribl Stream addresses the root cause by introducing robust validation checks that prevent symbolic link resolution outside of intended directories during Git repository imports, effectively closing this attack pathway.