Graylog Allows Session Takeover via Insufficient HTML Sanitization
Date: 2025-05
Affected: maven/org.graylog2:graylog2-server, maven/org.graylog2:graylog2-server
Attack vector: xss
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2025-46827
CWE: CWE-79
CVSS: 8 (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H)

### Impact It is possible to obtain user session cookies by submitting an HTML form as part of an Event Definition Remediation Step field. For this attack to succeed, the attacker needs a user account with permissions to create event definitions, while the user must have permissions to view alerts. Additionally, an active Input must be present on the Graylog server that is capable of receiving form data (e.g. a HTTP input, TCP raw or syslog etc). ### Patches ### Workarounds None, as long as the relatively rare prerequisites are met. Analysis provided by Fabian Yamaguchi - Whirly Labs (Pty) Ltd


Mitigations:

Architectural layers (MAESTRO):