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Medium severity · published Apr 21, 2026
CVE-2026-6675
Responsive Blocks <= 2.2.0 - Unauthenticated Open Email Relay via REST API 'email_to' Parameter
5.3
CVSS
0.3%
EPSS
No
On KEV
Description
The Responsive Blocks – Page Builder for Blocks & Patterns plugin for WordPress is vulnerable to Unauthenticated Open Email Relay in all versions up to, and including, 2.2.0. This is due to insufficient authorization checks and missing server-side validation of the recipient email address supplied via a public REST API route. This makes it possible for unauthenticated attackers to send arbitrary emails to any recipient of their choosing through the affected WordPress site's mail server, effectively turning the site into an open mail relay.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 25% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RB
Responsive Blocks – Page Builder for Blocks & Patterns · cyberchimps
through 2.2.0 · source: vendor
Affected product
RB
Responsive Blocks – Page Builder for Blocks & Patterns
cyberchimps
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-6675
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-6675
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/browser/responsive-block-editor-addons/tags/2.1.9/includes/class-responsive-block-editor-addons.php#L2212
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/browser/responsive-block-editor-addons/tags/2.1.9/includes/class-responsive-block-editor-addons.php#L2324
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/browser/responsive-block-editor-addons/tags/2.1.9/includes/class-responsive-block-editor-addons.php#L2403
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/browser/responsive-block-editor-addons/trunk/includes/class-responsive-block-editor-addons.php#L2212
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/browser/responsive-block-editor-addons/trunk/includes/class-responsive-block-editor-addons.php#L2324
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/browser/responsive-block-editor-addons/trunk/includes/class-responsive-block-editor-addons.php#L2403
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