Flatastic permits unauthenticated cross-site scripting

Flatastic <= 2.0 allows an unauthenticated attacker to supply script-capable input that reaches browser output without adequate neutralization. The CNA vector requires victim interaction and assigns changed scope with low confidentiality, integrity and availability impact. Script executes in the site's origin when a victim interacts with the affected output.

CVE / CNA score 7.1 CVSS 3.1 · audit@patchstack.com

NVD score Pending NVD has not published its own CVSS assessment.

Component: Flatastic
Plugin slug: flatastic
Affected: n/a through 2.0
Safe version: See mitigation notes
Published: Aug 20, 2026
Weakness: CWE-79 — Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

This CVE was published Aug 20, 2026 and is one of 2 known issues for this theme.

What to do

Update, patch or deactivate.

No fixed release is identified for CVE-2026-66673. Update Flatastic when a release newer than 2.0 is confirmed to fix this issue; until then, deactivate or remove the affected component when the site's risk warrants it. Review activity by the stated attacker class and investigate unexpected data access, state changes, files or sessions relevant to this vulnerability class.

No confirmed safe version is listed. Consider a vendor-supported patch or temporarily restricting the affected functionality while you assess the risk.

Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.

Source record

Technical description

Unauthenticated Cross Site Scripting (XSS) in Flatastic <= 2.0 versions.

CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L

References

Primary and upstream sources

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