How severe is CVE-2021-3986?

CVE-2021-3986 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2021-3986 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3986?

CVE-2021-3986 affects Janeczku Calibre-web. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3986?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2021-3986 have an EU (EUVD) identifier?

Yes. CVE-2021-3986 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-3282.

When was CVE-2021-3986 published?

CVE-2021-3986 was published on 2024-11-15 and last updated on 2026-06-17.

CVE-2021-3986

CVE-2021-3986 is a medium-severity vulnerability in Janeczku Calibre-web with a CVSS 3.x base score of 4.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-209.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 0% (28th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2024-3282
Weakness: CWE-209
Affected product: Janeczku Calibre-web
Published: 2024-11-15
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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.
How severe is CVE-2021-3986?: CVE-2021-3986 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2021-3986 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3986?: CVE-2021-3986 affects Janeczku Calibre-web. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3986?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2021-3986 have an EU (EUVD) identifier?: Yes. CVE-2021-3986 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-3282.
When was CVE-2021-3986 published?: CVE-2021-3986 was published on 2024-11-15 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:janeczku:calibre-web:*:*:*:*:*:*:*:*

More vulnerabilities in Janeczku Calibre-web

CVE-2022-0939 — Critical (CVSS 9.9): Server-Side Request Forgery (SSRF) in GitHub repository janeczku/calibre-web prior to 0.6.18.
CVE-2022-0767 — Critical (CVSS 9.9): Server-Side Request Forgery (SSRF) in GitHub repository janeczku/calibre-web prior to 0.6.17.
CVE-2025-7404 — Critical (CVSS 9.8): Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') vulnerability in Calibre…
CVE-2023-2106 — Critical (CVSS 9.8): Weak Password Requirements in GitHub repository janeczku/calibre-web prior to 0.6.20.
CVE-2022-2525 — Critical (CVSS 9.8): Improper Restriction of Excessive Authentication Attempts in GitHub repository janeczku/calibre-web prior to 0.6.20.
CVE-2022-30765 — Critical (CVSS 9.8): Calibre-Web before 0.6.18 allows user table SQL Injection.

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