CVE-2018-0732 | Client DoS due to large DH parameter

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).

Published: 2018-06-12 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-0732 is rated Moderate Risk (64.4/100): CVSS High severity, with high exploitation likelihood (EPSS 78.38%, 99th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2018-0732

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-28 78.59% 78.38% -0.21%
2 2026-03-24 79.77% 78.59% -1.18%
3 2026-03-18 — 79.77% —

Full EPSS history (56 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-0732

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2018-0732

OS Trackers for CVE-2018-0732

vendor priority summary link
alpine high CVE-2018-0732: 1 source package rows (libressl); 10 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 10, open 0. https://security.alpinelinux.org/vuln/CVE-2018-0732
debian low CVE-2018-0732 low priority: Debian including 1 source packages (openssl), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2018-0732
gentoo normal CVE-2018-0732: 1 GLSA(s) (201811-03), 1 atom(s) (dev-libs/openssl); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2018-0732
redhat medium — https://access.redhat.com/security/cve/CVE-2018-0732
suse medium CVE-2018-0732 severity moderate: SUSE including 577 source package names (0.1.75:openssl-1.1.0i-3.3.1, 0.9.1:libopenssl1_0_0-1.0.2j-60.30.1, …), 1152 product×package rows across 149 product lines (Container caasp/v4/caaspctl-tooling, Container caasp/v4/cilium, … (149 product lines)): Fixed 760, Known Not Affected 235, Known Affected 157. https://www.suse.com/security/cve/CVE-2018-0732/
ubuntu low CVE-2018-0732 low priority: Ubuntu including 3 source packages (openssl, openssl098, openssl1.0), 21 status rows across 7 suites (artful, bionic, cosmic, disco, trusty, upstream, xenial): DNE 10, released 8, needs-triage 3. https://ubuntu.com/security/CVE-2018-0732

Affected software / configurations for CVE-2018-0732

Vendor Product Version Raw CPE
openssl openssl >= 1.0.2, <= 1.0.2o cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
openssl openssl >= 1.1.0, <= 1.1.0h cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
canonical ubuntu_linux 12.04 cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:esm:*:*:*
canonical ubuntu_linux 14.04 cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 16.04 cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 17.10 cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:*
canonical ubuntu_linux 18.04 cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
nodejs node.js >= 6.0.0, < 6.8.1 cpe:2.3:a:nodejs:node.js:*:*:*:*:-:*:*:*
nodejs node.js >= 6.9.0, < 6.14.4 cpe:2.3:a:nodejs:node.js:*:*:*:*:lts:*:*:*
nodejs node.js >= 8.0.0, < 8.8.1 cpe:2.3:a:nodejs:node.js:*:*:*:*:-:*:*:*
nodejs node.js >= 8.9.0, < 8.11.4 cpe:2.3:a:nodejs:node.js:*:*:*:*:lts:*:*:*
nodejs node.js >= 10.0.0, < 10.9.0 cpe:2.3:a:nodejs:node.js:*:*:*:*:-:*:*:*

References for CVE-2018-0732

URL Tags
http://www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html Patch Third Party Advisory
http://www.securityfocus.com/bid/104442 Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1041090 Third Party Advisory VDB Entry
https://access.redhat.com/errata/RHSA-2018:2552 Third Party Advisory
https://access.redhat.com/errata/RHSA-2018:2553 Third Party Advisory
https://access.redhat.com/errata/RHSA-2018:3221 Third Party Advisory
https://access.redhat.com/errata/RHSA-2018:3505 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:1296 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:1297 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:1543 Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-419820.pdf Third Party Advisory
https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=3984ef0b72831da8b3ece4745cac4f8575b19098
https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=ea7abeeabf92b7aca160bdd0208636d4da69f4f4
https://lists.debian.org/debian-lts-announce/2018/07/msg00043.html Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EWC42UXL5GHTU5G77VKBF6JYUUNGSHOM/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y3IVFGSERAZLNJCK35TEM2R4726XIH3Z/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZBEV5QGDRFUZDMNECFXUSN5FMYOZDE4V/
https://nodejs.org/en/blog/vulnerability/august-2018-security-releases/ Vendor Advisory
https://security.gentoo.org/glsa/201811-03 Third Party Advisory
https://security.netapp.com/advisory/ntap-20181105-0001/ Third Party Advisory
https://security.netapp.com/advisory/ntap-20190118-0002/ Third Party Advisory
https://securityadvisories.paloaltonetworks.com/Home/Detail/133 Third Party Advisory
https://usn.ubuntu.com/3692-1/ Third Party Advisory
https://usn.ubuntu.com/3692-2/ Third Party Advisory
https://www.debian.org/security/2018/dsa-4348 Third Party Advisory
https://www.debian.org/security/2018/dsa-4355 Third Party Advisory
https://www.openssl.org/news/secadv/20180612.txt Vendor Advisory
https://www.oracle.com/security-alerts/cpuapr2020.html Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2021.html Third Party Advisory
https://www.oracle.com/technetwork/security-advisory/cpuapr2019-5072813.html Patch Third Party Advisory
https://www.oracle.com/technetwork/security-advisory/cpujan2019-5072801.html Patch Third Party Advisory
https://www.oracle.com/technetwork/security-advisory/cpujul2019-5072835.html Patch Third Party Advisory
https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html Patch Third Party Advisory
https://www.tenable.com/security/tns-2018-12 Third Party Advisory
https://www.tenable.com/security/tns-2018-13 Third Party Advisory
https://www.tenable.com/security/tns-2018-14 Third Party Advisory
https://www.tenable.com/security/tns-2018-17 Third Party Advisory
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