advplyr audiobookshelf up to 2.33.1 File Existence pathexists String.startsWith path traversal

Summaryinfo

A vulnerability marked as critical has been reported in advplyr audiobookshelf up to 2.33.1. Affected is the function String.startsWith of the file /api/filesystem/pathexists of the component File Existence Handler. This manipulation causes path traversal. The identification of this vulnerability is CVE-2026-42885. It is possible to initiate the attack remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in advplyr audiobookshelf up to 2.33.1. It has been declared as critical. Affected by this vulnerability is the function String.startsWith of the file /api/filesystem/pathexists of the component File Existence Handler. The manipulation with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. As an impact it is known to affect confidentiality. The summary by CVE is:

Audiobookshelf is a self-hosted audiobook and podcast server. Prior to 2.32.2, the POST /api/filesystem/pathexists endpoint uses String.startsWith() to validate that a resolved file path is within a library folder. This check fails for sibling directories whose names share a common prefix (e.g., /audiobooks vs /audiobooks-private), allowing authenticated users with upload permission to probe file existence outside their authorized library folder boundaries. This vulnerability is fixed in 2.32.2.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-42885 since 04/30/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

Upgrading to version 2.33.2 eliminates this vulnerability.

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Productinfo

Vendor

• advplyr

Name

• audiobookshelf

Version

• 2.33.0
• 2.33.1

Website

• Product: https://github.com/advplyr/audiobookshelf/

CPE 2.3info

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CPE 2.2info

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