CVE-2026-66596 describes an unauthenticated Cross Site Scripting (XSS) vulnerability in Newsletter software versions <= 9.3.3. The vulnerability allows remote attackers to execute arbitrary scripts in the context of the affected application without requiring authentication. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L) indicates network attack vector, low attack complexity, no privileges required, user interaction required, scope changed, and impacts on confidentiality, integrity, and availability at a low level. No patch or remediation details are provided in the available data.

Successful exploitation could allow attackers to execute arbitrary scripts in users' browsers, potentially leading to data theft, session hijacking, or other malicious actions affecting confidentiality, integrity, and availability. The vulnerability is exploitable remotely without authentication but requires user interaction. The scope is changed, meaning the vulnerability affects resources beyond the vulnerable component.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, consider applying any recommended workarounds or temporary mitigations from the vendor. Monitor official sources for updates regarding patches or fixes.