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CVE-2020-14145

Published: 29 June 2020

The client side in OpenSSH 5.7 through 8.4 has an Observable Discrepancy leading to an information leak in the algorithm negotiation. This allows man-in-the-middle attackers to target initial connection attempts (where no host key for the server has been cached by the client). NOTE: some reports state that 8.5 and 8.6 are also affected.

Notes

AuthorNote
seth-arnold
openssh-ssh1 is provided for compatibility with old devices that
cannot be upgraded to modern protocols. Thus we may not provide security
support for this package if doing so would prevent access to equipment.
mdeslaur
Per the advisory, "The developers of OpenSSH are not planning to
change the behavior of OpenSSH regarding this issue"
We will not be releasing updates for Ubuntu for this issue.

On 2020-12-02, it was announced that a partial mitigation has
been commited by OpenSSH developers:
https://www.openwall.com/lists/oss-security/2020/12/02/1
sbeattie
partial mitigation landed in openssh 8.4p1
litios
OpenSSH cannot be patch to fully mitigate this CVE as patching it
would disable the reordering of host key algorithms, breaking
RFC 4253. The partial mitigation disables this reordering
only in a single specific situation. Marking as deferred.
ccdm94
patching this issue in trusty and xenial has been considered
risky. Therefore, these releases will be marked as ignored.
Priority

Low

CVSS 3 base score: 5.9

Status

Package Release Status
openssh
Launchpad, Ubuntu, Debian
bionic Deferred

eoan Ignored
(reached end-of-life)
focal Deferred

groovy Ignored
(reached end-of-life)
hirsute Ignored
(reached end-of-life)
impish Ignored
(reached end-of-life)
jammy Deferred

kinetic Deferred

precise Ignored
(end of ESM support, was needed)
trusty Ignored
(see notes)
upstream Deferred

xenial Ignored
(see notes)
Patches:
upstream: https://anongit.mindrot.org/openssh.git/commit/?id=b3855ff053f5078ec3d3c653cdaedefaa5fc362d
openssh-ssh1
Launchpad, Ubuntu, Debian
bionic Deferred

eoan Ignored
(reached end-of-life)
focal Deferred

groovy Ignored
(reached end-of-life)
hirsute Ignored
(reached end-of-life)
impish Ignored
(reached end-of-life)
jammy Deferred

kinetic Deferred

precise Does not exist

trusty Does not exist

upstream Ignored
(frozen on openssh 7.5p)
xenial Does not exist