CVE-2018-0732

CVE-2018-0732 is a high-severity vulnerability in Openssl with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 49% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-320.

Key facts

Description

During key agreement in a TLS handshake using a DH(E) based ciphersuite a malicious server can send a very large prime value to the client. This will cause the client to spend an unreasonably long period of time generating a key for this prime resulting in a hang until the client has finished. This could be exploited in a Denial Of Service attack. Fixed in OpenSSL 1.1.0i-dev (Affected 1.1.0-1.1.0h). Fixed in OpenSSL 1.0.2p-dev (Affected 1.0.2-1.0.2o).

Frequently asked questions

What is CVE-2018-0732?
During key agreement in a TLS handshake using a DH(E) based ciphersuite a malicious server can send a very large prime value to the client. This will cause the client to spend an unreasonably long period of time generating a key for this prime resulting in a hang until the client has finished. This could be exploited in a Denial Of Service attack. Fixed in OpenSSL 1.1.0i-dev (Affected 1.1.0-1.1.0h). Fixed in OpenSSL 1.0.2p-dev (Affected 1.0.2-1.0.2o).
How severe is CVE-2018-0732?
CVE-2018-0732 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2018-0732 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 49% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-0732?
CVE-2018-0732 primarily affects Openssl. In total, 9 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-0732?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-0732 published?
CVE-2018-0732 was published on 2018-06-12 and last updated on 2026-06-17.

References

Affected products (9)

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Threat intelligence

Threat-intel indicators referencing this CVE: