CVE-2023-3817

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.

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