CVE-2023-6621Public exploitNetwork attack vector

Administrator-session script execution via reflected msg parameter

Published Jan 3, 2024 · Updated Jun 18, 2025

Reflected XSS in WPExperts Post SMTP before 2.8.7 allows remote attackers to execute script in an administrator's browser. The configuration-wizard admin page writes the msg query parameter into its response without sanitization or output escaping. Exploitation requires an administrator to open a crafted URL while authenticated, allowing script to act within that administrator's WordPress session.

CVSS severity6.1
Medium
EPSS probability0.40%
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 WPExperts Post SMTP before 2.8.7 allows remote attackers to execute script in an administrator's browser. The configuration-wizard admin page writes the msg query parameter into its response without sanitization or output escaping. Exploitation requires an administrator to open a crafted URL while authenticated, allowing script to act within that administrator's WordPress session.

The record

CVE
CVE-2023-6621
Published
Jan 3, 2024
Updated
Jun 18, 2025
Vendor
WPExperts
Product
Post SMTP
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 3, 2024CVE publishedPublication date reported by the CVE source.
  2. Jun 18, 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 <2.8.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

WPExperts · Post SMTPversion=0 <2.8.7

Published CVSS scores

6.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/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
Privilegesunauthenticated
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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