Bug 2452021 (CVE-2026-33711)

Summary: CVE-2026-33711 incus: Incus: Local privilege escalation or denial of service via predictable temporary file paths
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Incus, a system container and virtual machine manager. A local attacker could exploit a vulnerability in the API responsible for retrieving VM screenshots. By creating symbolic links (symlinks) in predictable temporary file paths, an attacker could trick Incus into truncating and altering arbitrary files on the filesystem. This could lead to a denial of service or, in specific configurations where the `protected_symlinks` kernel security feature is disabled, a local privilege escalation.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2452045, 2452046    
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Description OSIDB Bzimport 2026-03-26 23:02:05 UTC 
Incus is a system container and virtual machine manager. Incus provides an API to retrieve VM screenshots. That API relies on the use of a temporary file for QEMU to write the screenshot to which is then picked up and sent to the user prior to deletion. As versions prior to 6.23.0 use predictable paths under /tmp for this, an attacker with local access to the system can abuse this mechanism by creating their own symlinks ahead of time. On the vast majority of Linux systems, this will result in a "Permission denied" error when requesting a screenshot. That's because the Linux kernel has a security feature designed to block such attacks, `protected_symlinks`. On the rare systems with this purposefully disabled, it's then possible to trick Incus intro truncating and altering the mode and permissions of arbitrary files on the filesystem, leading to a potential denial of service or possible local privilege escalation. Version 6.23.0 fixes the issue.