Bug 2352944 (CVE-2025-27512)

Summary: CVE-2025-27512 zincati: Zincati allows unprivileged access to rpm-ostree D-Bus `Deploy()` and `FinalizeDeployment()` methods
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in Zincati, an auto-update agent for Fedora CoreOS hosts. This vulnerability may allow an unprivileged user with access to the system D-Bus socket to deploy older Fedora CoreOS versions, which may have other known vulnerabilities, and reboot the system into the deployed update via a logic error in the polkit rule.
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Bug Depends On: 2352973, 2352974    
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Description OSIDB Bzimport 2025-03-17 15:01:41 UTC 
Zincati is an auto-update agent for Fedora CoreOS hosts. Zincati ships a polkit rule which allows the `zincati` system user to use the actions `org.projectatomic.rpmostree1.deploy` to deploy updates to the system and `org.projectatomic.rpmostree1.finalize-deployment` to reboot the system into the deployed update. Since Zincati v0.0.24, this polkit rule contains a logic error which broadens access of those polkit actions to any unprivileged user rather than just the `zincati` system user. In practice, this means that any unprivileged user with access to the system D-Bus socket is able to deploy older Fedora CoreOS versions (which may have other known vulnerabilities). Note that rpm-ostree enforces that the selected version must be from the same branch the system is currently on so this cannot directly be used to deploy an attacker-controlled update payload. This primarily impacts users running untrusted workloads with access to the system D-Bus socket. Note that in general, untrusted workloads should not be given this access, whether containerized or not. By default, containers do not have access to the system D-Bus socket. The logic error is fixed in Zincati v0.0.30. A workaround is to manually add a following polkit rule, instructions for which are available in the GitHub Security Advisory.