CVE-2021-28975Public exploitNetwork attack vector

Administrator-session script execution via unencoded server fields

Published Oct 21, 2021 · Updated Aug 3, 2024

Stored cross-site scripting in WP Mailster 1.6.18.0 allows remote attackers to run JavaScript in a WordPress administrator's browser. The mst_servers page echoes stored server_host, server_name, and connection_parameter values into HTML without output encoding. The direct path requires a logged-in administrator to open the server details; missing anti-CSRF validation also lets a malicious site deliver the payload to an active administrator session.

CVSS severity6.1
Medium
EPSS probability0.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in WP Mailster 1.6.18.0 allows remote attackers to run JavaScript in a WordPress administrator's browser. The mst_servers page echoes stored server_host, server_name, and connection_parameter values into HTML without output encoding. The direct path requires a logged-in administrator to open the server details; missing anti-CSRF validation also lets a malicious site deliver the payload to an active administrator session.

The record

CVE
CVE-2021-28975
Published
Oct 21, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 21, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/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')
T1189Drive-by Compromise

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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