CVE-2025-0521Network attack vector

Stored XSS via unescaped mail metadata

Published Feb 18, 2025 · Updated Apr 8, 2026

Stored XSS in Post SMTP 3.0.2 and earlier allows remote attackers to inject scripts through the from and subject parameters. The plugin stores insufficiently sanitized from and subject values and later renders them into plugin pages without adequate output escaping. No authentication is required to plant the payload, but execution occurs only when a user opens an affected page, enabling script execution in that user's browser context.

CVSS severity7.2
High
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 Post SMTP 3.0.2 and earlier allows remote attackers to inject scripts through the from and subject parameters. The plugin stores insufficiently sanitized from and subject values and later renders them into plugin pages without adequate output escaping. No authentication is required to plant the payload, but execution occurs only when a user opens an affected page, enabling script execution in that user's browser context.

The record

CVE
CVE-2025-0521
Published
Feb 18, 2025
Updated
Apr 8, 2026
Vendor
Fullworks Plugins
Product
Post SMTP
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 18, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 8, 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=0 <=3.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fullworks Plugins · Post SMTPversion=0 <=3.0.2

Published CVSS scores

7.2WordfenceCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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 exploitUnconfirmed

Weakness, pattern, technique

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

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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