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CVE Record

CVE-2023-3817: Excessive time spent checking DH q parameter value

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.

MediumCVSS 5.3Not KEV-listedUpdated
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2023-3817 can make some OpenSSL-based applications spend excessive CPU time checking malicious or oversized Diffie-Hellman parameters. The practical business risk is denial of service in software that validates DH keys or parameters from untrusted sources. OpenSSL states its SSL/TLS implementation and OpenSSL 3.0/3.1 FIPS providers are not affected.

Executive priority

Prioritize normal security update cycles, with faster handling for internet-facing services that validate user-supplied cryptographic parameters. This is a denial-of-service issue with limited availability impact, not a confidentiality or integrity compromise in the cited sources.

Technical view

The issue affects DH_check(), DH_check_ex(), and EVP_PKEY_param_check() when processing a q parameter larger than p. That unnecessary check can cause long computation. The OpenSSL dhparam and pkeyparam command-line tools are also affected when used with -check. CVSS is 5.3, CWE-606, availability-only impact.

Likely exposure

Exposure is most likely in applications, management tools, import workflows, or validation services that accept DH keys or parameters from untrusted users and call the affected OpenSSL checks. Standard OpenSSL SSL/TLS usage is not in scope per the advisory.

Exploitation context

The provided sources do not show known active exploitation, and KEV is false. Abuse requires getting a vulnerable application or OpenSSL command-line validation workflow to check attacker-controlled DH parameters. Impact is delay or resource exhaustion, not data theft or code execution.

Researcher notes

Focus analysis on call paths that validate DH parameters outside normal TLS handshakes. The important boundary is whether q can be attacker-controlled and oversized before reaching OpenSSL parameter checks. Patch references exist for OpenSSL 3.1.2, 3.0.10, 1.1.1v, and 1.0.2zi.

Mitigation direction

  • Upgrade to OpenSSL releases containing the vendor fix for the deployed branch.
  • Apply distribution or appliance vendor security updates that include the OpenSSL patch.
  • Avoid checking DH parameters from untrusted sources until patched.
  • Limit or reject unexpectedly large untrusted DH parameter inputs before OpenSSL validation.
  • Review vendor guidance for products embedding OpenSSL rather than assuming system OpenSSL coverage.

Validation and detection

  • Inventory OpenSSL versions and linked copies across applications, containers, and appliances.
  • Search code for DH_check(), DH_check_ex(), and EVP_PKEY_param_check() usage.
  • Identify workflows that import or validate DH keys or parameters from untrusted sources.
  • Check scripts for openssl dhparam -check or pkeyparam -check on external input.
  • Confirm SSL/TLS-only services are not misclassified as affected without separate parameter-checking logic.
Prepared
Confidence
high
Sources
7

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-606: Exact CWE lookup

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cve · low confidence lookup

CVE-2023-3817 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.3 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
11Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
5.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L3.91.4Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.3Medium
CVSS 3.1 vector shape for CVE-2023-3817Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
OpenSSLOpenSSL3.1.0, 3.0.0, 1.1.1, 1.0.2unaffected
Weakness

CWE details

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-606 · source CWE mapping

Unchecked Input for Loop Condition

Unchecked Input for Loop Condition represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.