CVE-2026-71209
audiobookshelf: %2F Encoding Discrepancy Bypasses Cover/Image Auth Exemption Regex, Enabling Unauthenticated Path Traversal
Description
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.
INFO
Published Date :
Aug. 5, 2026, 8:16 a.m.
Last Modified :
Aug. 5, 2026, 8:16 a.m.
Remotely Exploit :
Yes !
Source :
309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c
Affected Products
The following products are affected by CVE-2026-71209
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c | ||||
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Apply the latest security patch for Audiobookshelf.
- Review and sanitize all user-supplied input for path components.
- Implement strict validation on file path requests.
- Restrict service account read permissions to essential files.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-71209.
| URL | Resource |
|---|---|
| https://github.com/advplyr/audiobookshelf | |
| https://github.com/advplyr/audiobookshelf/security/advisories/GHSA-pg8v-5jcv-wrvw |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-71209 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-71209
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-71209 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-71209 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c
Aug. 05, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'advplyr', 'product': 'audiobookshelf', 'versions': [{'status': 'affected', 'version': '2.19.1', 'versionType': 'custom', 'lessThanOrEqual': '2.35.1'}], 'programFiles': ['server/routers/Auth.js', 'server/managers/CacheManager.js'], 'defaultStatus': 'unknown'}] Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Added CWE CWE-22 Added Reference https://github.com/advplyr/audiobookshelf Added Reference https://github.com/advplyr/audiobookshelf/security/advisories/GHSA-pg8v-5jcv-wrvw