Single Mailchimp <= 1.4 - Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode Attributes

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Summary

CVECVE-2026-8868
StatePUBLISHED
AssignerWordfence
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-27 07:16:16 UTC
Updated2026-05-27 14:50:47 UTC
DescriptionThe Single Mailchimp plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'single-mailchimp' shortcode in all versions up to, and including, 1.4. This is due to insufficient input sanitization and output escaping on user-supplied shortcode attributes (autocomplete, label, placeholder, btn_text, success_msg, error_msg) which are concatenated directly into HTML output by the single_mailchimp() function in shortcodes.php. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

Risk And Classification

Primary CVSS: v3.1 6.4 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

EPSS: 0.000290000 probability, percentile 0.087030000 (date 2026-05-31)

Problem Types: CWE-79 | CWE-79 CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary6.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
3.1CNADECLARED6.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Jonathan-robrecht Single Mailchimp affected 1.4 semver Not specified

References

ReferenceSourceLinkTags
www.wordfence.com/threat-intel/vulnerabilities/id/070616c9-b6a3-43d9-a82d-5cbcf... [email protected] www.wordfence.com
plugins.trac.wordpress.org/browser/single-mailchimp/trunk/shortcodes.php [email protected] plugins.trac.wordpress.org
plugins.trac.wordpress.org/browser/single-mailchimp/trunk/shortcodes.php [email protected] plugins.trac.wordpress.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Gilang Asra Bilhadi (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-05-26T17:25:05.000ZDisclosed
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