CVE-2023-3817
MediumCVSS 5.3Exploitation Probability (EPSS)
High risk83th percentile - higher than 83% of all known CVEs
Summary
The issue is that checking excessively long DH keys or parameters may be very slow. Applications using the functions DH_check(), DH_check_ex(), or EVP_PKEY_param_check() may experience long delays, which could lead to a Denial of Service attack if the keys or parameters are obtained from an untrusted source.
Risk Assessment
Organizations may be vulnerable to Denial of Service attacks if applications use DH keys or parameters from untrusted sources, potentially leading to prolonged delays in system operations.
Recommendation
It is recommended to avoid using DH keys or parameters from untrusted sources and to implement additional checks to prevent passing excessively large parameter values to the DH_check() function.
Original NVD description (English source)
Issue summary: Checking excessively long DH keys or parameters may be very slow. Impact summary: Applications that use the functions DH_check(), DH_check_ex() or EVP_PKEY_param_check() to check a DH key or DH parameters may experience long delays. Where the key or parameters that are being checked have been obtained from an untrusted source this may lead to a Denial of Service. The function DH_check() performs various checks on DH parameters. After fixing CVE-2023-3446 it was discovered that a large q parameter value can also trigger an overly long computation during some of these checks. A correct q value, if present, cannot be larger than the modulus p parameter, thus it is unnecessary to perform these checks if q is larger than p. An application that calls DH_check() and supplies a key or parameters obtained from an untrusted source could be vulnerable to a Denial of Service attack. The function DH_check() is itself called by a number of other OpenSSL functions. An application calling any of those other functions may similarly be affected. The other functions affected by this are DH_check_ex() and EVP_PKEY_param_check(). Also vulnerable are the OpenSSL dhparam and pkeyparam command line applications when using the "-check" option. The OpenSSL SSL/TLS implementation is not affected by this issue. The OpenSSL 3.0 and 3.1 FIPS providers are not affected by this issue.