Use-After-Free Vulnerability in Linux Kernel Affecting 9p Client Operations

CVE-2026-63795

What is CVE-2026-63795?

A vulnerability exists in the Linux kernel associated with the 9p client operations where improper reference counting of the fid may lead to a use-after-free scenario. This happens when the p9_client_walk() function encounters an error after sending a request, dropping a reference to the oldfid even though it may still be in use. If this reference is released while the oldfid is expected to be valid, it can result in a critical security issue, allowing subsequent operations on the oldfid to lead to unexpected behavior or crashes. The patch ensures that fid is only released when it does not alias oldfid, preventing potential exploitation.

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