Advisory · CVE-2026-107360
Sandbox escape in rubygem-safemode lets template authors delete Satellite hosts
A flaw in rubygem-safemode lets an authenticated attacker who can supply template content bypass the Jail allow-list and invoke arbitrary methods on objects exposed to the template renderer, including host deletion. Red Hat rates it critical at CVSS 9.6.
- Vendor
- Red Hat
- Product
- Red Hat Satellite 6
- Identifier / CWE
- CVE-2026-107360
CWE-183 - Action timing
- Immediate
Explain it like I’m five
Satellite lets certain users write small template scripts, but only with a short list of safe actions allowed. A trick with compound assignments skips the safety check, so a template author can reach destructive buttons like deleting a host.
- 01Template access
An authenticated attacker with permission to supply template content reaches Satellite's template renderer.
- 02Compound assignment
The attacker writes a compound assignment expression in the sandboxed code.
- 03Jail bypassed
The expression is evaluated without mediating method calls through the Jail allow-list, so the sandbox check is skipped.
- 04Destructive methods reached
The attacker invokes arbitrary no-argument methods on objects exposed to the renderer, including destructive operations such as host deletion and disclosure of non-allow-listed object state.
What happened
A flaw in rubygem-safemode affects Red Hat Satellite 6. Red Hat describes it as compound assignment expressions in sandboxed code being evaluated without mediating method calls through the Jail allow-list: an authenticated attacker who can supply template content can invoke arbitrary no-argument methods on objects exposed to the template renderer without Jail mediation, including destructive operations such as host deletion and disclosure of non-allow-listed object state. Red Hat rates it critical at CVSS 9.6, with network access, low privileges, no user interaction, and changed scope.
Red Hat’s published mitigation is to restrict template edit privileges to trusted administrators until a fixed safemode release is deployed, and where feasible to avoid exposing highly privileged ActiveRecord objects to untrusted template authors. No fixed release is named in the vendor bulletin at the time of writing, so no fixed version is claimed here.
The sandbox was the only thing standing between a template author and the objects behind the template. With the allow-list skipped, a low-privilege user who can edit a provisioning template can reach the same destructive operations an administrator can.
What to do
- Inventory Satellite deployments and identify every account with template edit privileges.
- Restrict template edit privileges to trusted administrators immediately, and remove template authoring from any account that does not need it.
- Review Satellite templates for compound assignment expressions and other unusual constructs, especially in templates edited by lower-privilege users.
- Review Satellite audit logs for unexpected host deletions, template changes, and access to non-allow-listed object state.
- Watch for the fixed safemode release from Red Hat and deploy it when available, then re-check template privileges.
- Verify that template authoring is limited to trusted administrators after remediation.
Management note
A 9.6 sandbox escape with no patch yet is a permissions problem first and a patching problem second. Cut the template author list to people you would trust with host deletion, because until the fix lands, that is effectively what template editing grants.