advplyr audiobookshelf up to 2.35.1 Authentication Exemption Check server/routers/Auth.js CacheManager.handleCoverCache ID information disclosure

Summaryinfo

A vulnerability, which was classified as problematic, has been found in advplyr audiobookshelf up to 2.35.1. The impacted element is the function CacheManager.handleCoverCache of the file server/routers/Auth.js of the component Authentication Exemption Check. This manipulation of the argument ID causes information disclosure. This vulnerability is tracked as CVE-2026-71209. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in advplyr audiobookshelf up to 2.35.1. It has been declared as problematic. Affected by this vulnerability is the function CacheManager.handleCoverCache of the file server/routers/Auth.js of the component Authentication Exemption Check. The manipulation of the argument id with an unknown input leads to a information disclosure vulnerability. The CWE definition for the vulnerability is CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. As an impact it is known to affect confidentiality. The summary by CVE is:

audiobookshelf's authentication-exemption check (server/routers/Auth.js) matches unauthenticated-allowed GET routes against req.path via a regex requiring a literal /items/:id/cover or /authors/:id/image shape, where req.path retains %2F sequences URL-encoded. Express's router decodes the :id route parameter before handler code runs, so a %2F-encoded '../' sequence in :id (e.g. ..%2f..%2f..%2ftmp%2fpwned) passes the literal-path auth-exemption check while resolving to a real path-traversal payload once decoded. CacheManager.handleCoverCache then joins this decoded value into a cache file path and streams the result before any database-backed ownership check. This bypasses the fix applied for CVE-2025-25205 (which anchored the exemption regex and switched it to req.path) and results in unauthenticated arbitrary file read of any file matching the pattern *_<width>[x<height>].<ext> that the service account can read.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-71209 since 08/05/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/05/2026). The attack technique deployed by this issue is T1592 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-53206). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• advplyr

Name

• audiobookshelf

Version

• 2.35.0
• 2.35.1

Website

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

CPE 2.3info

• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Discussion