Description
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."
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | libssh | 0.6.3-4.3 | — |
| Debian 13 | libssh | 0.6.3-4.3 | — |
| Debian 12 | libssh | 0.6.3-4.3 | — |
| Debian 8 | libssh | 0.6.3-4+deb8u2 | DSA-3488-1 |
| Debian 7 | libssh | 0.5.4-1+deb7u3 | DSA-3488-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 6.0 | libssh | 0.4.5-3+squeeze3 | DLA-425-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | libssh | 0.6.3-4.2ubuntu1 | — |
| Ubuntu 14.04 LTS | libssh | 0.6.1-0ubuntu3.3 | USN-2912-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Rhel Extras Other 7 | libssh +1 | 0.7.1-2.el7 | RHSA-2016:0566 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP1 | libssh | 0.6.3-11.1 | SUSE-SU-2016:0625-1 |
| SLES 12 | libssh | 0.6.3-11.1 | SUSE-SU-2016:0625-1 |
| SLES 11 SP4 | libssh | 0.2-5.22.1 | SUSE-SU-2016:0622-1 |
Advisories 7
- USN-2912-1 libssh vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DLA-425-1 libssh - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3488-1 libssh - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2016:0625-1 Security update for libssh SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2016:0622-1 Security update for libssh SUSE / openSUSE Security Updates · Feb 4, 2026
- RHSA-2016:0566 Red Hat Security Advisory: libssh security update Red Hat Security Advisories (RHSA) · Nov 22, 2025
- WID-SEC-2024-1054 libssh: Mehrere Schwachstellen BSI CERT-Bund (WID) · May 7, 2024
References
- FEDORA-2016-d9f950c779 vendor-advisory
- USN-2912-1 vendor-advisory
- https://www.libssh.org/security/advisories/CVE-2016-0739.txt
- https://puppet.com/security/cve/CVE-2016-0739
- FEDORA-2016-dc9e8da03c vendor-advisory
- GLSA-201606-12 vendor-advisory
- DSA-3488 vendor-advisory
- RHSA-2016:0566 vendor-advisory
- https://www.libssh.org/2016/02/23/libssh-0-7-3-security-and-bugfix-release/
- openSUSE-SU-2016:0880 vendor-advisory