CVE-2021-3988: Calibreweb Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-r735-9gc6-2hvq
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CVSS 6.1
CWE-79
Published
Advisory Summary

CVE-2021-3988 is a MODERATE (CVSS 6.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Calibreweb libraries in the PyPI ecosystem. The issue involves cross-site scripting (xss) - dom in janeczku/calibre-web. Remediation is available by upgrading affected packages to version 0.6.15.

CVE-2021-3988 at a Glance

CVE Identifier CVE-2021-3988
GHSA Identifier GHSA-r735-9gc6-2hvq
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Calibreweb
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 6.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N).

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

How to Fix CVE-2021-3988

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-2021-3988, 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-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. 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

A Cross-site Scripting (XSS) vulnerability exists in janeczku/calibre-web, specifically in the file `edit_books.js`. The vulnerability occurs when editing book properties, such as uploading a cover or a format. The affected code directly inserts user input into the DOM without proper sanitization, allowing attackers to execute arbitrary JavaScript code. This can lead to various attacks, including stealing cookies. The issue is present in the code handling the `#btn-upload-cover` change event.

CVE-2021-3988 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-2021-3988 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-3988
Security Fix Commit FIX COMMIT
https://github.com/janeczku/calibre-web/commit/7ad419dc8c12180e842a82118f4866ac3d074bc5
Calibreweb Source Repository REPOSITORY
https://github.com/janeczku/calibre-web
huntr.com/bounties/fa4c8fd1-7... WEB
https://huntr.com/bounties/fa4c8fd1-7846-4dad-9112-2c07461f0609

Frequently Asked Questions

What is CVE-2021-3988?
CVE-2021-3988 is a security vulnerability in Calibreweb involving Cross-site Scripting (XSS) - DOM in janeczku/calibre-web under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Calibreweb versions are affected?
Affected versions include releases prior to 0.6.15 across affected packages: calibreweb.
What version fixes CVE-2021-3988?
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-2021-3988?
CVE-2021-3988 has a CVSS v3.1 base score of 6.1 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2021-3988?
CVE-2021-3988 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check PyPI dependencies for CVE-2021-3988?
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 
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  "schema_version" : "1.4.0",
  "id" : "GHSA-r735-9gc6-2hvq",
  "modified" : "2024-11-19T20:47:47Z",
  "published" : "2024-11-15T12:31:44Z",
  "aliases" : [ "CVE-2021-3988" ],
  "summary" : "Cross-site Scripting (XSS) - DOM in janeczku/calibre-web",
  "details" : "A Cross-site Scripting (XSS) vulnerability exists in janeczku/calibre-web, specifically in the file `edit_books.js`. The vulnerability occurs when editing book properties, such as uploading a cover or a format. The affected code directly inserts user input into the DOM without proper sanitization, allowing attackers to execute arbitrary JavaScript code. This can lead to various attacks, including stealing cookies. The issue is present in the code handling the `#btn-upload-cover` change event.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "calibreweb"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
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      }, {
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      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-3988"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/janeczku/calibre-web/commit/7ad419dc8c12180e842a82118f4866ac3d074bc5"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/janeczku/calibre-web"
  }, {
    "type" : "WEB",
    "url" : "https://huntr.com/bounties/fa4c8fd1-7846-4dad-9112-2c07461f0609"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-11-15T20:52:00Z",
    "nvd_published_at" : "2024-11-15T11:15:06Z"
  }
}