CVE-2021-25964Network attack vector

Victim-session script execution via unsanitized descriptions

Published Oct 4, 2021 · Updated Apr 30, 2025

Stored XSS in Calibre-Web 0.6.0 through 0.6.12 allows remote authenticated users to execute JavaScript when a victim opens a book. The edit_book_comments path stores description HTML without sanitization, and detail views render that persisted content. Metadata-edit permission and victim interaction are required; successful exploitation can read or change data available to the victim's browser session.

CVSS severity5.4
Medium
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Calibre-Web 0.6.0 through 0.6.12 allows remote authenticated users to execute JavaScript when a victim opens a book. The edit_book_comments path stores description HTML without sanitization, and detail views render that persisted content. Metadata-edit permission and victim interaction are required; successful exploitation can read or change data available to the victim's browser session.

The record

CVE
CVE-2021-25964
Published
Oct 4, 2021
Updated
Apr 30, 2025
Vendor
Calibre-Web
Product
Calibre-Web
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Apr 30, 2025Record 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=0.6.0 <unspecified
  2. Affected versionversion=unspecified <=0.6.12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Calibre-Web · Calibre-Webversion=0.6.0 <unspecified; version=unspecified <=0.6.12

Published CVSS scores

5.4MendCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.5NVDAV:N/AC:M/Au:S/C:N/I:P/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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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