CVE-2022-0778 Siemens CVE debrief

Who should care

OT and industrial network operators using affected Siemens SCALANCE wireless devices; administrators who import, validate, or manage external certificates and keys; and teams responsible for device firmware maintenance in environments that rely on certificate-based access or trust stores.

Technical summary

The underlying flaw is in OpenSSL’s BN_mod_sqrt() handling of non-prime moduli. When certificate parsing reaches code paths for elliptic curve public keys in compressed form or explicit elliptic curve parameters, a crafted certificate or private key can cause the function to loop forever. Because parsing occurs before certificate signature verification, simply presenting a maliciously crafted object to a susceptible parser can be enough to cause a denial-of-service event.

Defensive priority

High. The published CVSS score is 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), and the main operational risk is service hang or parser lockup on externally supplied certificate/key content.

Recommended defensive actions

• Upgrade affected Siemens SCALANCE devices to V6.6.0 or later, as directed by Siemens.
• Inventory SCALANCE models and firmware versions against the affected product list in the advisory before maintenance windows.
• Limit exposure to untrusted certificate and private-key inputs wherever operationally possible, especially in workflows that ingest externally supplied material.
• Validate certificate and key handling paths in OT operations plans so a hang in parsing does not disrupt critical availability or recovery procedures.

Evidence notes

The source corpus links the vulnerability description to the Siemens SCALANCE advisory ICSA-26-111-07 / SSA-019200, which states that affected products run versions earlier than 6.6.0 and that remediation is to update to 6.6.0 or later. The advisory also states the issue can be reached while parsing crafted certificates or private keys containing explicit elliptic curve parameters. CISA’s source item revision history shows publication on 2026-04-14 and a CISA republication on 2026-04-21.

Official resources