Use of Client-Side Authentication in Płatnik

Summary

Płatnik performs client-side authentication. An attacker with access to any application instance connected to the backend server can bypass the login verification process and authenticate as an arbitrary user. This issue was fixed in metric 334 in version 10.02.002.

Remediation

1. Inventory every Zakład Ubezpieczeń Społecznych Płatnik deployment, including staging.
2. No fixed version appears in the public sources yet. Check the references below and the vendor directly.

References

• Advisoryhttps://cert.pl/posts/2026/10/CVE-2026-110970
• Referencehttps://www.zus.pl/firmy/program-platnik/o-programie-platnik