CVE-2026-89632

A flaw was found in the Linux kernel's Server Message Block (SMB) client. A malicious server could exploit this vulnerability by sending specially crafted data, leading to an out-of-bounds read. This occurs because the reparse_buf_ptr() function reads data before properly validating the buffer size, allowing it to access memory beyond the intended boundary.

An out-of-bounds read in the SMB client reparse buffer parser can occur because reparse_buf_ptr() reads ReparseDataLength before verifying that OutputCount covers the fixed reparse_data_buffer header. A malicious or compromised SMB server can return a short response with OutputCount smaller than 6, causing the client kernel to read past the received data while processing a reparse point response. For the CVSS the PR:N because the attacker does not need local privileges on the client and only needs the ability to act as or influence the SMB server response. UI:R is used because the client normally has to connect to or access the malicious SMB share. Impact is at least limited confidentiality exposure from a kernel out-of-bounds read and possible denial of service if the invalid read faults or is caught by hardening. No direct privilege escalation primitive is evident because the patch shows a read before validation and not a write or UAF.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.