Host root RCE via backup.yaml symlink following
Published Aug 21, 2026 · Updated Aug 21, 2026
Symlink following in Linux Containers Incus before 7.3.0 allows remote authenticated users to execute code as host root via a crafted image. The image unpacker preserves an attacker-supplied backup.yaml symlink, and UpdateInstanceBackupFile opens that path without a no-follow check while the daemon runs as root. A project-confined TLS or RBAC identity with can_create_images and can_create_instances can overwrite an arbitrary host file and compromise the host and other tenants.
Summary
What happened
Symlink following in Linux Containers Incus before 7.3.0 allows remote authenticated users to execute code as host root via a crafted image. The image unpacker preserves an attacker-supplied backup.yaml symlink, and UpdateInstanceBackupFile opens that path without a no-follow check while the daemon runs as root. A project-confined TLS or RBAC identity with can_create_images and can_create_instances can overwrite an arbitrary host file and compromise the host and other tenants.
The record
- CVE
- CVE-2026-63125
- Published
- Aug 21, 2026
- Updated
- Aug 21, 2026
- Vendor
- Linux Containers
- Product
- Incus
- Classifications
- CWE-61, CWE-59, T1068
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 21, 2026CVE publishedPublication date reported by the CVE source.
- Aug 21, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 7.3.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream backup.yaml symlink proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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