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Fencer Intel
medium 5.9

CVE-2016-0787 json

The diffie_hellman_sha256 function in kex.c in libssh2 before 1.7.0 improperly truncates secrets to 128 or 256 bits, which makes it easier…

published 2016-04-13 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-0800

cvss
5.9
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.6%
EPSS 2.6% chance of exploitation in 30 days, percentile 85%
public exploits
0
none known

Summary

The diffie_hellman_sha256 function in kex.c in libssh2 before 1.7.0 improperly truncates secrets to 128 or 256 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."

Patch / fix

  • libssh2 Debian 14, Debian 13, Debian 12 1.5.0-2.1

debian advisories DEBIAN-CVE-2016-0787

  • libssh2 Ubuntu 14.04 LTS 1.4.3-2ubuntu0.1
  • libssh2 Ubuntu 16.04 LTS 1.5.0-2ubuntu0.1

ubuntu advisories UBUNTU-CVE-2016-0787

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libssh2 RHEL 6 1.4.2-2.el6_7.1
  • libssh2 RHEL 7 1.4.3-10.el7_2.1

red hat advisories RHSA-2016:0428

  • libssh2_org SLES for SAP 11 SP4, SLES 11 SP4, SLED 11 SP4 +1 more 1.2.9-4.2.6.1
  • libssh2_org SLES for SAP 12 SP1, SLES for SAP 12, SLES 12 SP1 +5 more 1.4.3-16.1

suse advisories SUSE-SU-2016:0723-1SUSE-SU-2016:0718-1

  • libssh2_org openSUSE Tumbleweed 1.7.0-1.5

opensuse advisories openSUSE-SU-2024:10190-1

  • libssh2 Alpine 3.4 1.7.0-r0

alpine advisories ALPINE-CVE-2016-0787

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-0787 updated cvss 5.8

libssh2: bits/bytes confusion resulting in truncated Diffie-Hellman secret length

  • Red Hat Enterprise Linux Client (v. 7) libssh2 1.4.3-10.el7_2.1 Red Hat Enterprise Linux Client Optional (v. 7) libssh2 1.4.3-10.el7_2.1 Red Hat Enterprise Linux ComputeNode (v. 7) libssh2 1.4.3-10.el7_2.1 Red Hat Enterprise Linux ComputeNode Optional (v. 7) libssh2 1.4.3-10.el7_2.1 Red Hat Enterprise Linux Desktop (v. 6) libssh2 1.4.2-2.el6_7.1 Red Hat Enterprise Linux Desktop Optional (v. 6) libssh2 1.4.2-2.el6_7.1
    +10 more products
    Red Hat Enterprise Linux HPC Node (v. 6) libssh2 1.4.2-2.el6_7.1 Red Hat Enterprise Linux HPC Node Optional (v. 6) libssh2 1.4.2-2.el6_7.1 Red Hat Enterprise Linux Server (v. 6) libssh2 1.4.2-2.el6_7.1 Red Hat Enterprise Linux Server (v. 7) libssh2 1.4.3-10.el7_2.1 Red Hat Enterprise Linux Server Optional (v. 6) libssh2 1.4.2-2.el6_7.1 Red Hat Enterprise Linux Server Optional (v. 7) libssh2 1.4.3-10.el7_2.1 Red Hat Enterprise Linux Workstation (v. 6) libssh2 1.4.2-2.el6_7.1 Red Hat Enterprise Linux Workstation (v. 7) libssh2 1.4.3-10.el7_2.1 Red Hat Enterprise Linux Workstation Optional (v. 6) libssh2 1.4.2-2.el6_7.1 Red Hat Enterprise Linux Workstation Optional (v. 7) libssh2 1.4.3-10.el7_2.1
    fixed: vendor fix RHSA-2016:0428

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.59% chance of exploitation in the next 30 days, higher than 85% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 5.9 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.