CVE-2023-3817 — Issue summary: Checking excessively long DH keys or parameters may be very slow

Issue summary: Checking excessively long DH keys or parameters may be very slow.

01What is this vulnerability?

Issue summary: Checking excessively long DH keys or parameters may be very slow.

02Affected products

No structured affected-product list available — see references below for vendor advisories.

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2023-07-31T16:15:10.497
• Last modified: 2026-10-14T22:17:16.080

09References

• git.openssl.org — https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=6a1eb62c29db6cb5eec…
• git.openssl.org — https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=869ad69aadd985c7b8c…
• git.openssl.org — https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=9002fd07327a91f35ba…
• git.openssl.org — https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=91ddeba0f2269b017dc…
• www.openssl.org — https://www.openssl.org/news/secadv/20230731.txt
• seclists.org — http://seclists.org/fulldisclosure/2023/Jul/43
• www.openwall.com — http://www.openwall.com/lists/oss-security/2023/07/31/1
• www.openwall.com — http://www.openwall.com/lists/oss-security/2023/09/22/11
• www.openwall.com — http://www.openwall.com/lists/oss-security/2023/09/22/9
• www.openwall.com — http://www.openwall.com/lists/oss-security/2023/11/06/2