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Really Simple Security (Free) <= 9.8.2 — Unauthenticated Unbounded Option Growth

CVE-2026-88798Published · Updated

Action summary

Affected: ≤9.8.2Update to 9.8.3 or newer

All remediation steps
Watch plugin
Severity
Medium5.3
CVSS
5.3
CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
What does this vector mean?
AV:N Attack vector
Network
AC:L Attack complexity
Low
PR:N Privileges required
None
UI:N User interaction
None
S:U Scope
Unchanged
C:N Confidentiality
None
I:N Integrity
None
A:L Availability
Low
Weakness
CWE-400 Uncontrolled Resource Consumption
Required access
No account needed
Exploit prediction (EPSS)
0.4% chance in 30 days36th percentile
CISA KEV
Not listed
On this page8

Am I affected?

Really Simple Security – Simple and Performant Security (formerly Really Simple SSL) really-simple-ssl

  1. Affected≤ 9.8.2
  2. Patched in9.8.3

Update to 9.8.3 or newer.

You are affected if you run ≤ 9.8.2. Version 9.8.3 and later are not affected by this issue.

  • Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under Really Simple Security – Simple and Performant Security (formerly Really Simple SSL).
  • No admin access? Run a passive check of your site. It reads public files only.
  • No account is needed to exploit this. Treat any exposed site on an affected version as at risk.

What to do

  1. Update to version 9.8.3, or a newer patched version
  2. Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
  3. Watch Really Simple Security – Simple and Performant Security (formerly Really Simple SSL) to get an email when the next vulnerability is published.

Advisory

Source description from Wordfence Intelligence, credited to Naoki Kawahigashi.

The Really Simple Security (Free) plugin for WordPress is vulnerable to Denial of Service in all versions up to, and including, 9.8.2. This is due to missing validation on client-supplied IP headers used as storage keys in the rsssl_404_cache option, allowing arbitrary values from HTTP_CLIENT_IP and HTTP_X_FORWARDED_FOR to be written as array keys without bound. This makes it possible for unauthenticated attackers to grow the rsssl_404_cache option without bound by supplying arbitrary values in spoofed client IP headers, degrading site performance when handling 404 responses.

Exploits & references

Proof-of-concept & detection

No public proof-of-concept or detection template is known for this vulnerability.

Advisories & patches

More in Really Simple Security – Simple and Performant Security (formerly Really Simple SSL)

All 13
More vulnerabilities in Really Simple Security – Simple and Performant Security (formerly Really Simple SSL)
SeverityVulnerabilityCVEPublished
Medium4.3Missing Authorization to 2FA Bypass
≤9.8.1Update to 9.8.2
CVE-2026-82519
Medium5.3 Unauthenticated Two-Factor Authentication Bypass
≤9.8.0Update to 9.8.1
CVE-2026-89080
Medium5.3Unauthenticated Two-Factor Authentication Bypass
≤9.8.0Update to 9.8.1
CVE-2026-84777
High7.5Unauthenticated Denial of Service
≤9.8.0Update to 9.8.1
CVE-2026-84775
High8.8Authenticated (Custom Role+) Remote Code Execution
<9.8.0Update to 9.8.0
CVE-2026-81766

Timeline

  1. CVE published

    Severity medium, CVSS 5.3

  2. Record last updated

Sources & licenses

Wordfence record
Vulnerability data
Wordfence Intelligence. Copyright 2012-2026 Defiant Inc. Licensed under the CC BY-SA 4.0.
CVE® identifiers
Copyright 1999-2026 The MITRE Corporation. Used under the CVE Program. CVE® is a registered trademark of The MITRE Corporation.
CVSS / CWE
National Vulnerability Database (NVD), shown unmodified. This product uses the NVD API but is not endorsed or certified by the NVD.
EPSS
Exploit Prediction Scoring System by FIRST.org.
VulnCrest content
Summary, remediation guidance and page layout © VulnCrest. Not sourced from NVD.

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