CVE-2021-3987: Calibreweb Improper Access Control Vulnerability

MODERATE
Advisory Identifier: GHSA-fj5v-w2jp-wqvj
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CVSS 5.4
CWE-284 CWE-862
Published
Advisory Summary

CVE-2021-3987 is a MODERATE (CVSS 5.4) improper access control vulnerability (CWE-284: Improper Access Control) affecting Calibreweb libraries in the PyPI ecosystem. The issue involves improper access control in janeczku/calibre-web. Remediation is available by upgrading affected packages to version 0.6.15.

CVE-2021-3987 at a Glance

CVE Identifier CVE-2021-3987
GHSA Identifier GHSA-fj5v-w2jp-wqvj
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-284: Improper Access Control
Affected Product Calibreweb
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2021-3987

To remediate this vulnerability, upgrade all affected Calibreweb dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

calibreweb fixed: 0.6.15 
pip install calibreweb>=0.6.15
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show calibreweb

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2021-3987, inspect your installed packages using pip:

pip show calibreweb

Analyze the terminal output to locate any version of Calibreweb in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.6.15), your application is affected.

Note: The pip show calibreweb command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-284: Improper Access Control, where the product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. In Calibreweb, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2021-3987 Affected Calibreweb Versions

1 component(s)
Fixed Versions:
0.6.15
Product / Package Ecosystem Affected Versions Fixed Version
calibreweb
pypi/calibreweb
PyPI
< 0.6.15
0.6.15

References

NVD — CVE-2021-3987 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-3987
Security Fix Commit FIX COMMIT
https://github.com/janeczku/calibre-web/commit/bcdc97641447965af486964537f3821f47b28874
Calibreweb Source Repository REPOSITORY
https://github.com/janeczku/calibre-web
huntr.com/bounties/29fcc091-8... WEB
https://huntr.com/bounties/29fcc091-87b6-43bc-ab4b-3c0bec3f71df

Frequently Asked Questions

What is CVE-2021-3987?
CVE-2021-3987 is a security vulnerability in Calibreweb involving Improper Access Control in janeczku/calibre-web under CWE-284: Improper Access Control.
Which Calibreweb versions are affected?
Affected versions include releases prior to 0.6.15 across affected packages: calibreweb.
What version fixes CVE-2021-3987?
Upgrading to 0.6.15 (or the latest patched release for your respective branch) resolves the vulnerability.
Is calibreweb affected?
Yes, calibreweb is affected in releases prior to 0.6.15. Upgrade your dependency to 0.6.15 or later.
What is the CVSS score of CVE-2021-3987?
CVE-2021-3987 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2021-3987?
CVE-2021-3987 is classified under CWE-284: Improper Access Control (The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.).
How can I check PyPI dependencies for CVE-2021-3987?
Run the dependency tree command: 'pip show calibreweb'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fj5v-w2jp-wqvj",
  "modified" : "2024-11-15T20:51:30Z",
  "published" : "2024-11-15T12:31:44Z",
  "aliases" : [ "CVE-2021-3987" ],
  "summary" : "Improper Access Control in janeczku/calibre-web",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "calibreweb"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.6.15"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-3987"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/janeczku/calibre-web/commit/bcdc97641447965af486964537f3821f47b28874"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/janeczku/calibre-web"
  }, {
    "type" : "WEB",
    "url" : "https://huntr.com/bounties/29fcc091-87b6-43bc-ab4b-3c0bec3f71df"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-284", "CWE-862" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-11-15T20:51:30Z",
    "nvd_published_at" : "2024-11-15T11:15:06Z"
  }
}