Local privilege escalation via mismatched UID type
Published Aug 31, 2026 · Updated Sep 1, 2026
Authorization bypass in zbus_polkit before 5.1.0 allows local users to gain unauthorized privileges through a PID-reuse race. Subject::new_for_owner() encodes the unix-process subject UID as D-Bus unsigned type u instead of required signed type i, so polkit discards it and performs a racy PID lookup in /proc. Local users need low-privileged access, termination of an authorized process, and successful reuse of its PID; a win applies the terminated process's authorization to the new process.
Summary
What happened
Authorization bypass in zbus_polkit before 5.1.0 allows local users to gain unauthorized privileges through a PID-reuse race. Subject::new_for_owner() encodes the unix-process subject UID as D-Bus unsigned type u instead of required signed type i, so polkit discards it and performs a racy PID lookup in /proc. Local users need low-privileged access, termination of an authorized process, and successful reuse of its PID; a win applies the terminated process's authorization to the new process.
The record
- CVE
- CVE-2026-78422
- Published
- Aug 31, 2026
- Updated
- Sep 1, 2026
- Vendor
- z-galaxy
- Product
- zbus_polkit
- Classifications
- CWE-367, CWE-686, CAPEC-233, CAPEC-151, CAPEC-29, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 31, 2026CVE publishedPublication date reported by the CVE source.
- Sep 1, 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=0 <5.1.0
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
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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