CVE-2025-0588 in Octopus Server
Summary
by MITRE • 02/11/2025
In affected versions of Octopus Server it was possible for a user with sufficient access to set custom headers in all server responses. By submitting a specifically crafted referrer header the user could ensure that all subsequent server responses would return 500 errors rendering the site mostly unusable. The user would be able to subsequently set and unset the referrer header to control the denial of service state with a valid CSRF token whilst new CSRF tokens could not be generated.
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Analysis
by VulDB Data Team • 07/02/2025
The vulnerability identified as CVE-2025-0588 represents a critical server-side issue within Octopus Server versions that allows authenticated users with sufficient privileges to manipulate HTTP response headers through a crafted referrer header mechanism. This flaw exists in the server's response handling logic where custom headers can be set by users with appropriate access levels, creating a pathway for deliberate service disruption. The vulnerability specifically targets the server's ability to maintain consistent response behavior and introduces a condition where legitimate server operations become compromised through header manipulation. Security researchers have classified this issue as a server-side request forgery vulnerability that enables denial of service conditions through header injection techniques.
The technical implementation of this vulnerability stems from inadequate input validation and header processing within the Octopus Server's HTTP response handling module. When a user with sufficient access submits a specially crafted referrer header, the server's response generation logic incorrectly processes this input and sets internal response headers that cause subsequent server responses to return 500 internal server error codes. This occurs because the server's header processing routine fails to properly sanitize or validate the referrer header content before incorporating it into the response headers. The flaw creates a persistent state where the server becomes effectively unusable until the malicious header is removed, as the injected header maintains its influence over all subsequent responses. This represents a classic case of improper input sanitization and header handling that violates security best practices for web application development.
The operational impact of CVE-2025-0588 extends beyond simple service disruption to create a persistent denial of service condition that affects legitimate users and administrators. Once the malicious referrer header is set, all subsequent server operations become compromised and return 500 errors, effectively rendering the application unusable for all users except those who can directly manipulate the server configuration. The vulnerability's design allows for state control through header manipulation where users can toggle the denial of service condition on and off by setting or unsetting the referrer header, while maintaining the requirement for valid CSRF tokens to perform these operations. This creates a sophisticated attack vector that combines header injection with CSRF protection bypass mechanisms, making it particularly dangerous as it allows attackers to maintain control over the service state without requiring complete system compromise. The vulnerability's impact is amplified by the fact that new CSRF tokens cannot be generated, preventing legitimate users from recovering from the attack state through normal authentication mechanisms.
The security implications of this vulnerability align with CWE-79 and CWE-352 categories, representing cross-site request forgery and improper input validation weaknesses respectively. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 (Endpoint Denial of Service) and T1566.001 (Phishing with Social Engineering). Organizations using affected Octopus Server versions should immediately implement mitigations including input validation for all HTTP headers, particularly referrer headers, and implement rate limiting for header modification operations. The recommended approach involves disabling or sanitizing custom header functionality for non-privileged users, implementing comprehensive header validation routines, and establishing monitoring for unusual header modification patterns. Additionally, administrators should consider implementing automated response mechanisms that detect and reset malicious header states, while also ensuring that CSRF token generation mechanisms remain functional even under attack conditions. The vulnerability demonstrates the importance of proper input sanitization and the potential for authenticated users with insufficient privilege separation to cause significant operational disruptions through clever manipulation of server response handling logic.