CVE-2021-24232Public exploitNetwork attack vector

Authenticated script execution via unencoded license error

Published Apr 22, 2021 · Updated Aug 3, 2024

Reflected XSS in Advanced Booking Calendar before 1.6.8 allows remote authenticated users to execute script via a crafted settings request. The license-error branch in backend/settings.php prints the message query parameter into an HTML error notice without output encoding. A victim must be signed in and open the crafted settings-page URL; the injected script then runs in the victim's browser context.

CVSS severity5.4
Medium
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in Advanced Booking Calendar before 1.6.8 allows remote authenticated users to execute script via a crafted settings request. The license-error branch in backend/settings.php prints the message query parameter into an HTML error notice without output encoding. A victim must be signed in and open the crafted settings-page URL; the injected script then runs in the victim's browser context.

The record

CVE
CVE-2021-24232
Published
Apr 22, 2021
Updated
Aug 3, 2024
Vendor
Elbtide
Product
Advanced Booking Calendar
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 22, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=1.6.8 <1.6.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Elbtide · Advanced Booking Calendarversion=1.6.8 <1.6.8

Published CVSS scores

3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

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

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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