CVE-2026-71209

audiobookshelf - %2F Encoding Discrepancy Bypasses Cover/Image Auth Exemption Regex, Enabling Unauthenticated Path Traversal

Published Aug 5, 2026 CVSS 3.1 · 7.5 High EPSS 2.2% KEV · Not listed
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. CacheManager.handleCoverCache then joins this decoded value into a cache file path and streams the result before any database-backed ownership check.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values 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. 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. CacheManager.handleCoverCache then joins this decoded value into a cache file path and streams the result before any database-backed ownership check.
Type Values Removed Values Added
Title audiobookshelf: %2F Encoding Discrepancy Bypasses Cover/Image Auth Exemption Regex, Enabling Unauthenticated Path Traversal audiobookshelf - %2F Encoding Discrepancy Bypasses Cover/Image Auth Exemption Regex, Enabling Unauthenticated Path Traversal
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Advplyr
Advplyr audiobookshelf
Vendors & Products Advplyr
Advplyr audiobookshelf
Type Values Removed Values 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.
Title audiobookshelf: %2F Encoding Discrepancy Bypasses Cover/Image Auth Exemption Regex, Enabling Unauthenticated Path Traversal
Weaknesses CWE-22
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
TuranSec
Published
Updated
Aug 10, 2026, 11:45 AM
Reserved
Aug 5, 2026, 6:56 AM
Status
Deferred
Published
Aug 5, 2026, 8:16 AM
Modified
Oct 24, 2026, 3:10 PM