CVE-2026-0561
MediumShield Security <= 21.0.8 - Unauthenticated Reflected Cross-Site Scripting via 'message' Parameter
Published Feb 19, 2026 · Updated Apr 8, 2026 · Also known as cb49eb5f-c1ff-4440-8b53-c2515e65da27
Key Facts
Routine patching- CVE-2026-0561 is a medium-severity vulnerability (CVSS 6.1 v3.1) affecting wp-simple-firewall (wordpress-plugin), Shield: Blocks Bots, Protects Users, and Prevents Security Breaches.
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- EPSS estimates a 0.6% probability of exploitation in the next 30 days.
- Fixed versions are available, including wp-simple-firewall 21.0.10.
- Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.
CVSS v3.1
6.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS (30-day exploit likelihood)
0.6%
Higher than 50.0% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
None known
Get the full CVE-2026-0561 brief as a PDF
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Description
The Shield Security plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'message' parameter in all versions up to, and including, 21.0.8 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| wp-simple-firewallwordpress-plugin | See advisory | 21.0.10 |
| Shield: Blocks Bots, Protects Users, and Prevents Security Breaches | See advisory | n/a |
Patched Releases
wp-simple-firewall
21.0.10
Timeline
Publicly disclosed
Feb 19, 2026
Last updated
Apr 8, 2026
Weakness Type
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
References
- advisoryhttps://www.wordfence.com/threat-intel/vulnerabilities/id/cb49eb5f-c1ff-4440-8b53-c2515e65da27?source=api-prod
- advisoryhttps://www.wordfence.com/threat-intel/vulnerabilities/id/cb49eb5f-c1ff-4440-8b53-c2515e65da27?source=api-scan
- otherhttps://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=3439494%40wp-simple-firewall&new=3439494%40wp-simple-firewall&sfp_email=&sfph_mail=
- otherhttps://research.cleantalk.org/cve-2026-0561
- otherhttps://www.wordfence.com/threat-intel/vulnerabilities/id/cb49eb5f-c1ff-4440-8b53-c2515e65da27?source=cve
FAQ
Common Questions.
The Shield Security plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the 'message' parameter in all versions up to, and including, 21.0.8 due to insufficient input sanitization and output escaping.
Affected: wp-simple-firewall (wordpress-plugin); Shield: Blocks Bots, Protects Users, and Prevents Security Breaches. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including wp-simple-firewall 21.0.10.
Brandefense priority: routine patching, as no exploitation is known and its severity is moderate or low.
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