CVE-2018-10896

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2018-08-01 · updated 2026-06-17
Weakness: CWE-321

Description

The default cloud-init configuration, in cloud-init 0.6.2 and newer, included "ssh_deletekeys: 0", disabling cloud-init's deletion of ssh host keys. In some environments, this could lead to instances created by cloning a golden master or template system, sharing ssh host keys, and being able to impersonate one another or conduct man-in-the-middle attacks.

Affected products

Canonical Ltd. cloud-init: from 0.6.2 before 18.4 — fixed in 18.4

How to fix

Upgrade to a fixed version: Canonical Ltd. cloud-init 18.4. Check the vendor advisory for mitigations.

References

https://bugs.launchpad.net/cloud-init/+bug/1781094
https://bugzilla.redhat.com/show_bug.cgi?id=1574338
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10896
https://bugs.launchpad.net/cloud-init/+bug/1781094
https://bugzilla.redhat.com/show_bug.cgi?id=1574338
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10896

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