Medium severity · published Aug 30, 2026
CVE-2026-81766
Really Simple Security < 9.8.0 - Multisite Subsite Admin+ Arbitrary Plugin Installation via rsp_upgrade_install_plugin
6.6
CVSS
0.4%
EPSS
No
On KEV
Description
The Really Simple Security WordPress plugin before 9.8.0 does not check that the user is allowed to install Really Simple Security WordPress plugin before 9.8.0 before installing one from a user-supplied URL, allowing an administrator of a subsite on a multisite network to install and execute arbitrary code in the network-shared Really Simple Security WordPress plugin before 9.8.0 directory, which WordPress otherwise reserves to the network administrator. Exploitation requires the network administrator to have enabled the Really Simple Security WordPress plugin before 9.8.0 administration menu for subsites, which is not the default.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
High
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 38% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RS
Really Simple Security ·
before 9.8.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-81766
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-81766
wpscan.com
https://wpscan.com/vulnerability/948d70a2-605e-4a83-8feb-eca4dbb5f948/
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