CVE-2023-3446: Issue summary: Checking excessively long DH keys or parameters may be very slow. Impact summary: Applications that use the functions DH_check(), DH_c...

Description

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. One of those checks confirms that the modulus ('p' parameter) is not too large. Trying to use a very large modulus is slow and OpenSSL will not normally use a modulus which is over 10,000 bits in length. However the DH_check() function checks numerous aspects of the key or parameters that have been supplied. Some of those checks use the supplied modulus value even if it has already been found to be too large. An application that calls DH_check() and supplies a key or parameters obtained from an untrusted source could be vulernable 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.

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

5.53%

91.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Openssl	Openssl	1.0.2
Openssl	Openssl	1.1.1
Openssl	Openssl	3.0.0
Openssl	Openssl	3.1.0
Openssl	Openssl	3.1.1

References

https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=1fa20cf2f506113c761777127a38bce5068740ebMailing List, Patch, Vendor Advisory
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=8780a896543a654e757db1b9396383f9d8095528Mailing List, Patch, Vendor Advisory
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=9a0a4d3c1e7138915563c0df4fe6a3f9377b839cBroken Link, Vendor Advisory
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=fc9867c1e03c22ebf56943be205202e576aabf23Mailing List, Patch, Vendor Advisory
https://www.openssl.org/news/secadv/20230719.txtVendor Advisory
http://www.openwall.com/lists/oss-security/2023/07/19/4
http://www.openwall.com/lists/oss-security/2023/07/19/5
http://www.openwall.com/lists/oss-security/2023/07/19/6
http://www.openwall.com/lists/oss-security/2023/07/31/1
http://www.openwall.com/lists/oss-security/2024/05/16/1
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=1fa20cf2f506113c761777127a38bce5068740ebMailing List, Patch, Vendor Advisory
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=8780a896543a654e757db1b9396383f9d8095528Mailing List, Patch, Vendor Advisory
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=9a0a4d3c1e7138915563c0df4fe6a3f9377b839cBroken Link, Vendor Advisory
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=fc9867c1e03c22ebf56943be205202e576aabf23Mailing List, Patch, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2023/08/msg00019.html
https://security.gentoo.org/glsa/202402-08
https://security.netapp.com/advisory/ntap-20230803-0011/
https://www.openssl.org/news/secadv/20230719.txtVendor Advisory

Timeline

Published: Jul 19, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-3446?

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. One of those checks confirms that the modulus ('p' parameter) is not too large. Trying to use a very large modulus is slow and OpenSSL will not normally use a modulus which is over 10,000 bits in length. However the DH_check() function checks numerous aspects of the key or parameters that have been supplied. Some of those checks use the supplied modulus value even if it has already been found to be too large. An application that calls DH_check() and supplies a key or parameters obtained from an untrusted source could be vulernable 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.

How severe is CVE-2023-3446?

CVE-2023-3446 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 5.53% probability of exploitation in the next 30 days.

How do I fix CVE-2023-3446?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

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