CVE-2023-6237: OpenSSL

Medium severity, CVSS 5.9. EPSS: 2.3% chance of exploitation in the next 30 days.

Issue summary: Checking excessively long invalid RSA public keys may take a long time. Impact summary: Applications that use the function EVP_PKEY_public_check() to check RSA public keys may experience long delays. Where the key that is being checked has been obtained from an untrusted source this may lead to a Denial of Service. When function EVP_PKEY_public_check() is called on RSA public keys, a computation is done to confirm that the RSA modulus, n, is composite. For valid RSA keys, n is a product of two or more large primes and this computation completes quickly. However, if n is an overly large prime, then this computation would take a long time. An application that calls EVP_PKEY_public_check() and supplies an RSA key obtained from an untrusted source could be vulnerable to a Denial of Service attack. The function EVP_PKEY_public_check() is not called from other OpenSSL functions however it is called from the OpenSSL pkey command line application. For that reason that application is also vulnerable if used with the '-pubin' and '-check' options on untrusted data. The OpenSSL SSL/TLS implementation is not affected by this issue. The OpenSSL 3.0 and 3.1 FIPS providers are affected by this issue.

Affected products

• OpenSSL OpenSSL: from 3.0.0, before 3.0.13 (fixed in 3.0.13); from 3.1.0, before 3.1.5 (fixed in 3.1.5); from 3.2.0, before 3.2.1 (fixed in 3.2.1)
• Siemens SIMATIC s7-1500 TM Mfp - Gnu/linux Subsystem: any version
• Siemens Sinec Nms: before V3.0 SP1 (fixed in V3.0 SP1)

Published 2024-04-25. Last modified 2026-06-17.