CVE-2018-10896 — The default cloud-init configuration, in cloud-init 0

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 ss

01What is this vulnerability?

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.

02Affected products

Vendor	Product	Versions
Canonical	cloud	init — 0.6.2

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2018-08-01T17:00:00.000Z
• Last modified: 2024-08-05T07:54:36.167Z

09References

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