CVE-2021-3988Public exploitNetwork attack vector

Script execution via unsanitized upload filename

Published Nov 15, 2024 · Updated Nov 20, 2024

DOM-based XSS in Calibre-Web before 0.6.15 allows remote attackers to execute JavaScript through a crafted upload filename. The #btn-upload-cover and #btn-upload-format change handlers pass the selected filename to jQuery html() instead of rendering it as text. Execution requires a user to select the crafted file in the book-editing workflow, after which script runs in that user's browser and can access or alter page data.

CVSS severity6.1
Medium
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DOM-based XSS in Calibre-Web before 0.6.15 allows remote attackers to execute JavaScript through a crafted upload filename. The #btn-upload-cover and #btn-upload-format change handlers pass the selected filename to jQuery html() instead of rendering it as text. Execution requires a user to select the crafted file in the book-editing workflow, after which script runs in that user's browser and can access or alter page data.

The record

CVE
CVE-2021-3988
Published
Nov 15, 2024
Updated
Nov 20, 2024
Vendor
Calibre-Web
Product
Calibre-Web
Classifications
CWE-79, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 15, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 20, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <0.6.15
  2. Affected versionversion=unspecified <=latest

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Calibre-Web · Calibre-Webversion=0 <0.6.15; version=unspecified <=latest

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.7huntr.devCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.002Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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