CVE-2025-30373 in Server
Summary
by MITRE • 04/07/2025
Graylog is a free and open log management platform. Starting with 6.1, HTTP Inputs can be configured to check if a specified header is present and has a specified value to authenticate HTTP-based ingestion. Unfortunately, even though in cases of a missing header or a wrong value the correct HTTP response (401) is returned, the message will be ingested nonetheless. To mitigate the vulnerability, disable http-based inputs and allow only authenticated pull-based inputs. This vulnerability is fixed in 6.1.9.
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Analysis
by VulDB Data Team • 10/30/2025
The vulnerability identified as CVE-2025-30373 affects Graylog, a widely used open-source log management platform that processes and analyzes log data from various sources. This security flaw exists in Graylog versions starting from 6.1 and specifically impacts HTTP Inputs functionality, which serves as a critical component for receiving log data through HTTP-based ingestion methods. The vulnerability stems from a fundamental misconfiguration in the authentication mechanism where the system fails to properly enforce access controls during the ingestion process. While the platform correctly returns a 401 unauthorized HTTP response when authentication headers are missing or contain incorrect values, the system continues to process and store the incoming log messages regardless of the authentication failure.
This represents a classic case of improper access control implementation where the authorization check occurs after data processing rather than before it, creating a scenario where unauthorized data ingestion can occur despite the system's attempt to block access. The flaw allows attackers to bypass authentication mechanisms by sending HTTP requests with invalid or missing headers, yet still successfully deliver log data to the Graylog server. This creates a significant security risk as it enables potential attackers to inject malicious log data into the system without proper authorization, potentially leading to data integrity issues, log pollution, or even exploitation of other system components that might process these ingested messages.
From a technical perspective, this vulnerability aligns with CWE-285 (Improper Authorization) and falls under the ATT&CK technique T1070.004 (Indicator Removal on Host: File Deletion) and T1566.001 (Phishing: Spearphishing Attachment) when considering potential attack vectors that could leverage this weakness. The issue demonstrates a critical flaw in the input validation and access control flow where the system architecture permits data processing to continue even when authentication fails. The fact that Graylog correctly returns HTTP 401 responses indicates that the system recognizes the authentication failure, but fails to implement proper early termination of the ingestion process, creating a logical inconsistency in the security controls.
The operational impact of this vulnerability extends beyond simple unauthorized data ingestion, as it fundamentally undermines the security posture of log management operations. Organizations relying on Graylog for security monitoring and compliance may experience compromised log integrity, making it difficult to trust the data for forensic analysis or security incident response. The vulnerability essentially allows an attacker to perform a form of log injection attack, potentially leading to false positives in security alerts, masking actual security incidents, or even introducing malicious payloads that could be processed by downstream security tools. This creates a dangerous scenario where the very system designed to protect against security threats becomes a potential vector for data compromise.
Organizations using Graylog versions 6.1 through 6.1.8 should immediately implement mitigations to address this vulnerability, with the most effective approach being the disabling of HTTP-based inputs and transitioning to authenticated pull-based inputs for log collection. This recommendation aligns with the principle of least privilege and defense in depth strategies that are fundamental to secure system design. The vulnerability was resolved in Graylog version 6.1.9 through proper implementation of access control enforcement, ensuring that authentication failures properly prevent data ingestion from proceeding. Security teams should also conduct thorough audits of their Graylog configurations to ensure that no HTTP inputs remain enabled in production environments, and should consider implementing additional monitoring to detect unusual ingestion patterns that might indicate exploitation attempts.