ICSA-25-259-03: Siemens SIMATIC NET CP, SINEMA and SCALANCE

CISA's summary

Risk evaluation: Successful exploitation of these vulnerabilities could allow an attacker to cause a denial-of-service (DoS) condition in the affected devices by exploiting integer overflow bugs.

Products, as the advisory lists them

DeSpy has not checked any unit, hardware revision or firmware.

Vulnerabilities in this advisory

• CVE-2021-41990 · CWE-190

  The gmp plugin in strongSwan before version 5.9.4 has a remote integer overflow vulnerability via a crafted certificate with an RSASSA-PSS signature. For example, this can be triggered by an unrelated self-signed CA certificate sent by an initiator. Remote code execution cannot occur.

• CVE-2021-41991 · CWE-190

  The in-memory certificate cache in strongSwan before version 5.9.4 has a remote integer overflow vulnerability upon receiving many requests with different certificates to fill the cache and later trigger the replacement of cache entries. The code attempts to select a less-often-used cache entry by means of a random number generator, but this is not done correctly. This could lead to a denial of service (DoS) condition. Remote code execution can't be excluded completely, but it would require attackers to have control over the dereferenced memory, so it is very unlikely.

Acknowledgments, as the advisory lists them

• Siemens ProductCERT: reporting these vulnerabilities to CISA

The advisory's legal notice

All information products included in https://us-cert.cisa.gov/ics are provided "as is" for informational purposes only. The Department of Homeland Security (DHS) does not provide any warranties of any kind regarding any information contained within. DHS does not endorse any commercial product or service, referenced in this product or otherwise. Further dissemination of this product is governed by the Traffic Light Protocol (TLP) marking in the header. For more information about TLP, see https://us-cert.cisa.gov/tlp/.

Sources

• The advisory at cisa.gov
• The CSAF document (JSON)

DeSpy's copy of this version is dated 2026-09-28.