Answer in brief
CVE-2026-15421 records a Unknown severity vulnerability in Speed Optimizer <= 7.8.0 - Authenticated (Contributor+) Stored Cross-Site Scripting via Image Tag Attributes. The current sources do not mark it as known exploited. The current feed maps siteground/Speed Optimizer – The All-In-One Performance-Boosting Plugin (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps siteground/Speed Optimizer – The All-In-One Performance-Boosting Plugin (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| siteground/Speed Optimizer – The All-In-One Performance-Boosting Plugingeneric | 0 | Not reported |
Published upstream
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 19, 2026
The Speed Optimizer – The All-In-One Performance-Boosting Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Image Tag Attributes in all versions up to, and including, 7.8.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This is only exploitable when the site administrator has enabled the Lazy Load Media option in the plugin settings.
Quoted source text, attributed separately from HOL analysis.