CVE-2026-19264 in postiz-app
Summary
by MITRE • 08/07/2026
Postiz is an open-source social media scheduling tool. The route that serves locally stored media joins URL-supplied path segments onto the upload directory and streams the file without normalising the path or confining it to that directory, and the route requires no authentication. Raw dot-segments are collapsed before routing, but URL-encoded separators survive route matching and are decoded only once they reach the handler, restoring the traversal at the filesystem call. An unauthenticated remote attacker can therefore read any file readable by the application process, including the process environment, which exposes the JWT signing secret, the database connection string, and connected provider and billing secrets. Because session tokens are signed with that secret and carry no expiry, this allows forging a non-expiring session as any user, including an administrator, without a password.
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Analysis
by VulDB Data Team • 08/07/2026
This vulnerability exists within Postiz, an open-source social media scheduling platform, where a critical path traversal flaw compromises the application's security posture. The core issue stems from improper path handling in the media serving endpoint that concatenates user-supplied URL path segments directly onto the configured upload directory without proper sanitization or confinement. This design flaw allows attackers to manipulate file paths through URL-encoded traversal sequences that survive the initial routing phase but are decoded only at the handler level, effectively bypassing normal path normalization mechanisms.
The vulnerability operates through a specific attack vector involving raw dot-segment handling where URL-encoded separators such as %2e%2e%2f (which represents ../) pass through the routing layer unmodified and only get decoded during the final handler execution. This timing discrepancy enables attackers to traverse filesystem directories beyond the intended upload boundaries, effectively breaking out of the designated storage area. Since the affected route requires no authentication, malicious actors can exploit this weakness remotely without prior access credentials, making the vulnerability particularly dangerous in publicly accessible deployments.
The operational impact of this vulnerability extends far beyond simple file reading capabilities, as it grants attackers access to any files readable by the application process itself. This includes sensitive configuration files containing critical secrets such as JWT signing keys, database connection strings, and integration credentials for third-party services including billing providers and social media platforms. The exposure of these secrets creates a cascading security risk where attackers can not only read arbitrary files but also authenticate as any user within the system, including administrative accounts.
The JWT signing secret exposure represents the most severe consequence of this vulnerability, as it enables attackers to forge session tokens without knowledge of user passwords. These forged tokens carry no expiration time and grant full access privileges equivalent to legitimate administrators, allowing complete system compromise. This particular aspect aligns with attack patterns described in the attack technique matrix under T1566 for credential access and T1078 for valid accounts exploitation. The vulnerability also maps to CWE-22 Path Traversal, specifically addressing the issue of inadequate path normalization and insufficient input validation in file access operations.
Mitigation strategies must address both the immediate code-level fix and broader architectural security improvements. The primary solution involves implementing strict path normalization and confinement mechanisms that prevent any traversal outside the designated upload directory regardless of URL encoding or decoding phases. This requires proper sanitization of all user-supplied path components before any filesystem operations occur, ensuring that absolute paths and traversal sequences are rejected entirely. Additionally, authentication should be enforced for all file serving endpoints, and privilege separation should be implemented to limit the application's access to only necessary directories. The system should also adopt principle of least privilege by restricting file access permissions and implementing proper input validation at multiple layers including network, application, and filesystem levels to prevent similar vulnerabilities from manifesting in other components.