CVE-2023-5678
Issue summary: Generating excessively long X9.42 DH keys or checking excessively long X9.42 DH keys or parameters may be very slow.
Impact summary: Applications that use the functions DH_generate_key() to generate an X9.42 DH key may experience long delays. Likewise, applications that use DH_check_pub_key(), DH_check_pub_key_ex() or EVP_PKEY_public_check() to check an X9.42 DH key or X9.42 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.
While DH_check() performs all the necessary checks (as of CVE-2023-3817), DH_check_pub_key() doesn't make any of these checks, and is therefore vulnerable for excessively large P and Q parameters.
Likewise, while DH_generate_key() performs a check for an excessively large P, it doesn't check for an excessively large Q.
An application that calls DH_generate_key() or DH_check_pub_key() and supplies a key or parameters obtained from an untrusted source could be vulnerable to a Denial of Service attack.
DH_generate_key() and DH_check_pub_key() are also 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_pub_key_ex(), EVP_PKEY_public_check(), and EVP_PKEY_generate().
Also vulnerable are the OpenSSL pkey command line application when using the "-pubcheck" option, as well as the OpenSSL genpkey command line application.
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.
| Software | From | Fixed in |
|---|---|---|
| openssl / openssl | 1.0.2 | 1.0.2zj |
| openssl / openssl | 1.1.1 | 1.1.1x |
| openssl / openssl | 3.0.0 | 3.0.13 |
| openssl / openssl | 3.1.0 | 3.1.5 |
- http://www.openwall.com/lists/oss-security/2023/11/06/2
- http://www.openwall.com/lists/oss-security/2024/03/11/1
- https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=34efaef6c103d636ab507a0cc34dca4d3aecc055
- https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=710fee740904b6290fef0dd5536fbcedbc38ff0c
- https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=db925ae2e65d0d925adef429afc37f75bd1c2017
- https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=ddeb4b6c6d527e54ce9a99cba785c0f7776e54b6
- https://lists.debian.org/debian-lts-announce/2024/10/msg00033.html
- https://lists.debian.org/debian-lts-announce/2024/11/msg00000.html
- https://security.netapp.com/advisory/ntap-20231130-0010/
- https://www.openssl.org/news/secadv/20231106.txt
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A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
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Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
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