How severe is CVE-2021-3987?

CVE-2021-3987 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 none, integrity low, and availability none.

Is CVE-2021-3987 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-2021-3987?

CVE-2021-3987 affects Janeczku Calibre-web. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3987?

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

Does CVE-2021-3987 have an EU (EUVD) identifier?

Yes. CVE-2021-3987 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-3244.

When was CVE-2021-3987 published?

CVE-2021-3987 was published on 2024-11-15 and last updated on 2026-06-17.

CVE-2021-3987

CVE-2021-3987 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-862.

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-2024-3244
Weakness: CWE-862
Affected product: Janeczku Calibre-web
Published: 2024-11-15
Last modified: 2026-06-17

Description

An improper access control vulnerability exists in janeczku/calibre-web. The affected version allows users without public shelf permissions to create public shelves. The vulnerability is due to the `create_shelf` method in `shelf.py` not verifying if the user has the necessary permissions to create a public shelf. This issue can lead to unauthorized actions being performed by users.

Frequently asked questions

What is CVE-2021-3987?: An improper access control vulnerability exists in janeczku/calibre-web. The affected version allows users without public shelf permissions to create public shelves. The vulnerability is due to the `create_shelf` method in `shelf.py` not verifying if the user has the necessary permissions to create a public shelf. This issue can lead to unauthorized actions being performed by users.
How severe is CVE-2021-3987?: CVE-2021-3987 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 none, integrity low, and availability none.
Is CVE-2021-3987 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-2021-3987?: CVE-2021-3987 affects Janeczku Calibre-web. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3987?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2021-3987 have an EU (EUVD) identifier?: Yes. CVE-2021-3987 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-3244.
When was CVE-2021-3987 published?: CVE-2021-3987 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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