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

Q: How do I fix CVE-2023-3817?

openssl: upgrade to 3.0.10, 3.1.2. Exact commands for each OS are on this page.

Q: Is CVE-2023-3817 being exploited?

CVE-2023-3817 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2023-3817 affect?

CVE-2023-3817 affects openssl. Severity is medium (CVSS 5.3). 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

Q: How urgent is CVE-2023-3817?

Priority 50/100. Remotely exploitable, no login, no user action; On your watchlist

This month

MEDIUM 5.3REMOTEWATCHLISTUPGRADE

CVE-2023-3817 is a medium-severity flaw (CVSS 5.3) affecting openssl. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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. A

Why this priority

Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.0% (top 12%)
CISA exploited list	No
Weakness	CWE-606, CWE-834
Published	2023-07-31
Last modified	2026-10-14

Publisher (CNA): OpenSSL Software Foundation · Vendor: openssl

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-07-31 16:15 UTCPublished CVE record published
2026-10-14 22:17 UTCUpdated Record last modified

openssl openssl UPGRADE

Affected: >= 3.0.0 and < 3.0.10 · >= 3.1.0 and < 3.1.2 · 1.0.2 · 1.0.2 beta1 · 1.0.2 beta2 · 1.0.2 beta3 · 1.0.2a · 1.0.2b

Fixed in: 3.0.10, 3.1.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy openssl || rpm -q openssl || openssl --version

2. UPGRADE to 3.0.10 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade openssl

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openssl

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-3817?

openssl: upgrade to 3.0.10, 3.1.2. Exact commands for each OS are on this page.

Is CVE-2023-3817 being exploited?

CVE-2023-3817 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-3817 affect?

CVE-2023-3817 affects openssl. Severity is medium (CVSS 5.3). 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

How urgent is CVE-2023-3817?

Priority 50/100. Remotely exploitable, no login, no user action; On your watchlist

Software pages

OpenSSL vulnerabilities

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References

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