CVE-2024-7877Public exploitNetwork attack vector

Stored XSS via unescaped notification message

Published Nov 5, 2024 · Updated Nov 5, 2024

Stored XSS in Simply Schedule Appointments before 1.6.7.55 allows remote authenticated users to inject scripts through notification settings. The notification message field stores attacker-supplied HTML without sufficient sanitization or output escaping and renders it when the saved notification is viewed. Administrator privileges and a multisite installation or another configuration that disables unfiltered_html are required, and viewing the poisoned setting executes the script in that viewer's browser.

CVSS severity4.8
Medium
EPSS probability0.37%
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 Simply Schedule Appointments before 1.6.7.55 allows remote authenticated users to inject scripts through notification settings. The notification message field stores attacker-supplied HTML without sufficient sanitization or output escaping and renders it when the saved notification is viewed. Administrator privileges and a multisite installation or another configuration that disables unfiltered_html are required, and viewing the poisoned setting executes the script in that viewer's browser.

The record

CVE
CVE-2024-7877
Published
Nov 5, 2024
Updated
Nov 5, 2024
Vendor
NSquared
Product
Simply Schedule Appointments
Classifications
CWE-79, T1203
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Nov 5, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 5, 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 <1.6.7.55

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

NSquared · Simply Schedule Appointmentsversion=0 <1.6.7.55
N Squared Digital, LLC · Simply Schedule Appointmentsversion=0 <1.6.7.55

Published CVSS scores

4.8CISA ADPCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
4.4WordfenceCVSS:3.1/AV:N/AC:H/PR:H/UI:N/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
Privilegesadmin
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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