What is CVE-2021-3986?

CVE-2021-3986 is a medium-severity vulnerability in Janeczku Calibre-Web, classified under Generation of Error Message Containing Sensitive Information. CVSS score: 4.3/10. Published 2024-11-15.

How severe is CVE-2021-3986?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Information disclosure in Janeczku Calibre-Web

CVE-2021-3986

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.

Published 2024-11-15 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.004 (28.6th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 29th percentile — 28.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Janeczku Calibre-Web
Janeczku Janeczku/calibre-Web — versions unspecified

Weakness classification (CWE)

CWE-209 — Generation of Error Message Containing Sensitive Information

References

huntr.com/bounties/394af194-61a7-4e33-b373-877d4c766fca (Exploit, Patch, Third Party Advisory, Issue Tracking)
github.com/janeczku/calibre-web/commit/6f5390ead5df9779ac81fadefffb476e03f93548 (Patch)

Frequently asked questions

What is CVE-2021-3986?: CVE-2021-3986 is a medium-severity vulnerability in Janeczku Calibre-Web, classified under Generation of Error Message Containing Sensitive Information. CVSS score: 4.3/10. Published 2024-11-15.
How severe is CVE-2021-3986?: Medium severity. CVSS v3 base score is 4.3 out of 10.