CVE-2023-3817
Issue summary: Checking excessively long DH keys or parameters may be very slow.
Published Jul 31, 2023 · updated Oct 14, 2026 · OpenSSL OpenSSL
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.
Code
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No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Jul 31, 2023 · NIST NVD
Detected
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_che
Oct 14, 2026 · NIST NVD
Updated
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_che
Affected
- cpe openssl/opensslversion unspecified
- cpe openssl/openssl1.0.2
- cpe openssl/openssl1.0.2a
- cpe openssl/openssl1.0.2b
- vendor OpenSSL OpenSSLversion unspecified
Sources
- CIRCL Vulnerability LookupVulnerability recordCVE-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
vulnerability.circl.lu - CVE.orgVulnerability recordCVE-2023-3817
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2023-3817
30-day exploitation probability 3.0%
first.org - NIST NVDVulnerability recordCVE-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 tha
nvd.nist.gov