Cross-user lastlog access via wrapped offset
Published Sep 18, 2026 · Updated Sep 18, 2026
Integer overflow in Cockpit on Red Hat Enterprise Linux 9 and 10 allows local users with large UIDs to read and alter other users' lastlog records. The do_lastlog() function calculates a lastlog file offset from a specially provisioned UID in an ILP32 build, allowing the value to wrap and address the wrong record. Exploitation requires low-privileged authenticated access, an ILP32 build, and a sufficiently large UID; it does not provide code execution or privilege escalation.
Summary
What happened
Integer overflow in Cockpit on Red Hat Enterprise Linux 9 and 10 allows local users with large UIDs to read and alter other users' lastlog records. The do_lastlog() function calculates a lastlog file offset from a specially provisioned UID in an ILP32 build, allowing the value to wrap and address the wrong record. Exploitation requires low-privileged authenticated access, an ILP32 build, and a sufficiently large UID; it does not provide code execution or privilege escalation.
The record
- CVE
- CVE-2026-91142
- Published
- Sep 18, 2026
- Updated
- Sep 18, 2026
- Vendor
- Commonhaus Foundation
- Product
- Red Hat Enterprise Linux 10
- Classifications
- CWE-787, T1005, T1565.001
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 18, 2026CVE publishedPublication date reported by the CVE source.
- Sep 18, 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?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
What conditions does exploitation require?
What is affected?
Published CVSS scores
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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.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
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Technologies
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