CVE-2023-5678 Siemens CVE debrief

Who should care

Teams that use OpenSSL directly, especially applications that call DH_generate_key(), DH_check_pub_key(), DH_check_pub_key_ex(), EVP_PKEY_public_check(), or EVP_PKEY_generate(). Also relevant for users of the OpenSSL pkey command with -pubcheck and the genpkey command, particularly where DH inputs may be attacker-controlled.

Technical summary

The vulnerability is a resource-exhaustion problem caused by excessively large X9.42 DH keys or parameters. DH_check_pub_key() does not perform the same checks as DH_check(), leaving it vulnerable to oversized P and Q parameters. DH_generate_key() checks for an excessively large P, but not an excessively large Q. As a result, the affected API paths can take a long time to process malformed or oversized inputs, which can become a denial-of-service condition when those inputs are untrusted. NVD lists CWE-754 as the primary weakness and CWE-606 as a secondary weakness.

Defensive priority

Medium. Prioritize if your software accepts DH material from external or untrusted sources, or if you expose the affected OpenSSL APIs or CLI options in production workflows. The impact is availability-focused rather than confidentiality or integrity loss.

Recommended defensive actions

• Upgrade OpenSSL to a fixed release at or beyond 1.0.2zj, 1.1.1x, 3.0.13, or 3.1.5, depending on your branch.
• Inventory code and tooling that use DH_generate_key(), DH_check_pub_key(), DH_check_pub_key_ex(), EVP_PKEY_public_check(), EVP_PKEY_generate(), pkey -pubcheck, or genpkey.
• Treat DH keys and parameters from untrusted sources as high risk and validate or reject unexpectedly large inputs before calling the affected APIs.
• Confirm whether any affected usage is reachable from external or semi-trusted input paths, and prioritize those deployments first.
• Verify that your deployment is not relying on the affected API paths for SSL/TLS handling, since OpenSSL states the SSL/TLS implementation is not affected.

Evidence notes

This debrief is based on the supplied NVD record and OpenSSL vendor advisory reference list. The NVD record shows the vulnerability was published on 2023-11-06 and modified on 2026-05-12. The source corpus identifies affected versions as OpenSSL 1.0.2 through 1.0.2zj, 1.1.1 through 1.1.1x, 3.0.0 through 3.0.13, and 3.1.0 through 3.1.5. The corpus also states that SSL/TLS and the 3.0/3.1 FIPS providers are not affected.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.