CVE-2026-91142 vulnerability in Red Hat Products
Published on September 18, 2026
Cockpit: integer overflow in `do_lastlog()` offset calculation can misaddress `lastlog` entries on ilp32 builds
A flaw was found in Cockpit. An integer overflow vulnerability in the `do_lastlog()` function, specifically in the offset calculation for `lastlog` entries on ILP32 (Integer, Long, Pointer 32-bit) builds, can be exploited. A low-privileged authenticated user with a specially provisioned large User ID (UID) can cause the computed offset to wrap around. This allows the user to perform unauthorized reads and writes to other users' `lastlog` records, potentially disclosing or altering sensitive login accounting information.
Vulnerability Analysis
CVE-2026-91142 is exploitable with local system access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Timeline
Reported to Red Hat.
Made public. 123 days later.
Weakness Type
What is a Memory Corruption Vulnerability?
The software writes data past the end, or before the beginning, of the intended buffer. Typically, this can result in corruption of data, a crash, or code execution. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent write operation then produces undefined or unexpected results.
CVE-2026-91142 has been classified to as a Memory Corruption vulnerability or weakness.
Products Associated with CVE-2026-91142
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