Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
CVE-2026-81766
Unknown Really Simple Security — Really Simple Security < 9.8.0 - Multisite Subsite Admin+ Arbitrary Plugin Installation via rsp_upgrade_install_plugin
AV AC PR UI S C I A CVSS EPSS %ile KEV
N H H N U H H H 6.6 .0043 35.6 —
AFFECTED
Product Versions Fixed
Really Simple Security unspecified —
TIMELINE
Aug 27 Reserved by WPScan
Aug 30 Published (CNA: WPScan)
Aug 31 EXPLOIT PUBLISHED — CVE-2026-81766 (Unknown Really Simple Security). Public exploit reference added.
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.
Lifecycle
Complete event history — 3 events, chronological
| Date | Event | Detail |
|---|
| August 27, 2026 | Reserved | Reserved by WPScan |
| August 30, 2026 | Published | Published (CNA: WPScan) |
| August 31, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-81766 (Unknown Really Simple Security). Public exploit reference added. |
Affected
Affected products and packages — 1 row
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| Unknown | Really Simple Security | — | — | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-81766 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.
