CVE-2016-0739

libssh before 0.7.3 improperly truncates ephemeral secrets generated for the (1) diffie-hellman-group1 and (2) diffie-hellman-group14 key exchange methods to 128 bits, which makes it easier for man-in-the-middle attackers to decrypt or intercept SSH sessions via unspecified vectors, aka a "bits/bytes confusion bug."

Published: 2016-04-13 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-0739 is rated Moderate Risk (51/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.43%). Review affected assets and schedule 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-2016-0739

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 2026-06-15 3.78% 2.43% -1.35%
2 2026-05-25 3.66% 3.78% +0.12%
3 2026-05-13 — 3.66% —

Full EPSS history (23 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-0739

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.0 MEDIUM
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N 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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2016-0739

OS Trackers for CVE-2016-0739

vendor priority summary link
debian not yet assigned CVE-2016-0739 not yet assigned priority: Debian including 1 source packages (libssh), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2016-0739
gentoo normal CVE-2016-0739: 1 GLSA(s) (201606-12), 2 atom(s) (net-libs/libssh, net-libs/libssh2); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2016-0739
redhat medium — https://access.redhat.com/security/cve/CVE-2016-0739
suse medium CVE-2016-0739 severity moderate: SUSE including 18 source package names (14.28:libssh4-0.6.3-11.1, libssh, …), 47 product×package rows across 22 product lines (Container suse/sles12sp4, SUSE Linux Enterprise Desktop 11 SP4, … (22 product lines)): Fixed 41, Known Not Affected 6. https://www.suse.com/security/cve/CVE-2016-0739/
ubuntu medium CVE-2016-0739 medium priority: Ubuntu including 1 source packages (libssh), 6 status rows across 6 suites (precise, trusty, upstream, wily, xenial, yakkety): released 6. https://ubuntu.com/security/CVE-2016-0739

Affected software / configurations for CVE-2016-0739

Vendor Product Version Raw CPE
redhat enterprise_linux 7.0 cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
canonical ubuntu_linux 12.04 cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 14.04 cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 15.10 cpe:2.3:o:canonical:ubuntu_linux:15.10:*:*:*:*:*:*:*
libssh libssh <= 0.7.2 cpe:2.3:a:libssh:libssh:*:*:*:*:*:*:*:*
fedoraproject fedora 22 cpe:2.3:o:fedoraproject:fedora:22:*:*:*:*:*:*:*
fedoraproject fedora 23 cpe:2.3:o:fedoraproject:fedora:23:*:*:*:*:*:*:*
debian debian_linux 7.0 cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*

References for CVE-2016-0739

cvelogic Threat Intelligence