CVE-2021-3988

MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 53% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Elevated
6.1
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
6.1
EG Score
6.1(medium)
EPSS
27.7%
KEV
Not listed

Published

November 15, 2024

Last Modified

November 19, 2024

References (2)

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
calibreweb0.6.12, 0.6.13, 0.6.140.6.15—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 49× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-11 08:25 UTCEPSS rescore
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  24. 2026-06-25 17:16 UTCOSV refresh
  25. 2026-06-25 13:48 UTCEPSS rescore
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  1. 2026-06-25 13:48 UTCEPSS rescore
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  32. 2026-06-08 06:58 UTCOSV refresh
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  59. 2026-05-26 07:17 UTCEPSS rescore
  60. 2026-05-23 18:12 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-3988?
CVE-2021-3988 is a medium vulnerability published on November 15, 2024. 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,…
When was CVE-2021-3988 disclosed?
CVE-2021-3988 was first published in the National Vulnerability Database on November 15, 2024, with the most recent update on November 19, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-3988 actively exploited?
CVE-2021-3988 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 27.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-3988?
CVE-2021-3988 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2021-3988?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-3988, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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