CVE-2021-3988: A Cross-site Scripting (XSS) vulnerability exists in janeczku/calibre-web, specifically in the file `edit_book

Q: How do I fix CVE-2021-3988?

calibre-web: upgrade to 0.6.15. Exact commands for each OS are on this page.

Q: Is CVE-2021-3988 being exploited?

CVE-2021-3988 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-3988 affect?

CVE-2021-3988 affects calibre-web. Severity is medium (CVSS 6.1). 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 in

Q: How urgent is CVE-2021-3988?

Priority 34/100. Public exploit reference

Routine

MEDIUM 6.1UPGRADE

CVE-2021-3988 is a medium-severity flaw (CVSS 6.1) affecting calibre-web. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.4% (top 68%)
CISA exploited list	No
Weakness	CWE-79
Published	2024-11-15
Last modified	2026-06-17

Publisher (CNA): huntr.dev · Vendor: janeczku

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2024-11-15 11:15 UTCPublished CVE record published
2026-06-17 04:06 UTCUpdated Record last modified

janeczku calibre-web UPGRADE

Affected: < 0.6.15

Fixed in: 0.6.15

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy calibre-web || rpm -q calibre-web || calibre-web --version

2. UPGRADE to 0.6.15 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade calibre-web

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade calibre-web

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-3988?

calibre-web: upgrade to 0.6.15. Exact commands for each OS are on this page.

Is CVE-2021-3988 being exploited?

CVE-2021-3988 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-3988 affect?

CVE-2021-3988 affects calibre-web. Severity is medium (CVSS 6.1). 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 in

How urgent is CVE-2021-3988?

Priority 34/100. Public exploit reference

Related CVEs

CVE-2025-7404 CRITICAL 9.8 DOWNGRADE DOWNGRADE Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') vulnerability in Ca
CVE-2025-65858 LOW 3.5 DOWNGRADE A Stored Cross-Site Scripting (XSS) vulnerability in Calibre-Web v0.6.25 allows attackers to inject malicious
CVE-2024-39123 MEDIUM 5.4 UPGRADE In janeczku Calibre-Web 0.6.0 to 0.6.21, the edit_book_comments function is vulnerable to Cross Site Scripting
CVE-2021-3987 MEDIUM 4.3 UPGRADE An improper access control vulnerability exists in janeczku/calibre-web
CVE-2021-3986 MEDIUM 4.3 UPGRADE A vulnerability in janeczku/calibre-web allows unauthorized users to view the names of private shelves belongi

References

← Back to latest CVEs