CVE-2023-51520Network attack vector

Stored XSS via unescaped shortcode attributes

Published Feb 1, 2024 · Updated Apr 28, 2026

Stored XSS in wpdevelop Booking Calendar before 9.7.4 allows remote authenticated users to inject scripts through shortcode attributes. The plugin's shortcode handlers insufficiently sanitize user-supplied attributes and fail to escape them when generating page markup. Contributor-level access is required, and the script runs when another user views the affected page, enabling browser-context data access or page changes.

CVSS severity6.5
Medium
EPSS probability0.33%
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 wpdevelop Booking Calendar before 9.7.4 allows remote authenticated users to inject scripts through shortcode attributes. The plugin's shortcode handlers insufficiently sanitize user-supplied attributes and fail to escape them when generating page markup. Contributor-level access is required, and the script runs when another user views the affected page, enabling browser-context data access or page changes.

The record

CVE
CVE-2023-51520
Published
Feb 1, 2024
Updated
Apr 28, 2026
Vendor
wpdevelop
Product
Booking Calendar
Classifications
CWE-79, CAPEC-592, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 1, 2024CVE publishedPublication date reported by the CVE source.
  2. Apr 28, 2026Record 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=n/a <9.7.4 changes=[{"at":"9.7.4","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

wpdevelop · Booking Calendarversion=n/a <9.7.4 changes=[{"at":"9.7.4","status":"unaffected"}]

Published CVSS scores

6.4WordfenceCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
6.5PatchstackCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CAPEC-592Stored XSS
T1059.007JavaScript/JScript

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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