CVE-2026-75036: Fleet: DNS exfiltration via Sprig getHostByName in fleet.yaml Helm template preprocessing
A security vulnerability was discovered in Fleet's Helm template preprocessing where templates evaluated by the Fleet controller could reach network resources outside the management cluster. A user who can supply bundle content to a repository referenced by a GitRepo resource can cause the Fleet controller to: - Disclose cluster metadata available to the templating context. - Reveal information about hosts reachable from the controller's network position. Because the disclosure channel is name resolution, it may remain effective in environments where outbound traffic is otherwise restricted. The disclosed information is limited to values exposed to the Fleet templating context and to name resolution results. Integrity and availability of managed clusters are not affected.
This issue affects Fleet: from 0.12.0 before 0.12.19, from 0.13.0 before 0.13.15, from 0.14.0 before 0.14.10, from 0.15.0 before 0.15.6, and from 0.16.0 before 0.16.1.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Fleetto a version that resolves this vulnerability.Fixed in 0.12.19 - Upgrade
Upgrade
Fleetto a version that resolves this vulnerability.Fixed in 0.13.15 - Upgrade
Upgrade
Fleetto a version that resolves this vulnerability.Fixed in 0.14.10 - Upgrade
Upgrade
Fleetto a version that resolves this vulnerability.Fixed in 0.15.6 - Upgrade
Upgrade
Fleetto a version that resolves this vulnerability.Fixed in 0.16.1
Event History
Frequently Asked Questions
Who can realistically exploit this issue?
An attacker needs the ability to supply bundle content to a repository referenced by a GitRepo resource. The vulnerable templates are evaluated by the Fleet controller, so the controller's network position and templating context determine what can be reached or disclosed.
What information can be exposed?
The issue can disclose cluster metadata available in the Fleet templating context and information about hosts reachable from the controller's network position. Disclosure is limited to templating-context values and DNS resolution results; managed-cluster integrity and availability are not affected.
Does restricting general outbound traffic prevent exploitation?
Not necessarily. The disclosure channel is DNS name resolution, which may still work where other outbound traffic is restricted.
Which Fleet versions need remediation?
Affected releases are 0.12.0 through before 0.12.19, 0.13.0 through before 0.13.15, 0.14.0 through before 0.14.10, 0.15.0 through before 0.15.6, and 0.16.0 through before 0.16.1.