Vulnerability in Linux Kernel Affecting 32-bit Operations on s390 Architecture

CVE-2026-98869

What is CVE-2026-98869?

A vulnerability in the Linux kernel's BPF verifier compromises the handling of 32-bit operations on the s390 architecture. The flaw arises from broken zero-extension logic, which fails to correctly manage the semantics of 32-bit operations, potentially allowing for arbitrary values to be injected into the upper half of registers. The verifier's previous methods of tracking register liveness and zero extension minimalism have been altered, leading to situations where uninitialized values can breach security. A revised approach to register usage tracking aims to mitigate this issue, though it introduces a precision trade-off during function calls.

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