CVE-2026-72217

Received Received - Intake

Linux Kernel SUNRPC xdr_buf_to_bvec Buffer Overflow

Publication date: 2026-08-15

Last updated on: 2026-08-17

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: SUNRPC: Bound-check xdr_buf_to_bvec() stores before writing xdr_buf_to_bvec() writes a bio_vec into the caller's array before testing whether that slot is in range, and the head branch performs the store with no check at all. When the caller's budget is exactly used up, the next store lands one element past the end of the array. The overflow label returns count - 1, which masks the surplus store but cannot undo it. rq_bvec, the array passed by nfsd_vfs_write(), is allocated to exactly rq_maxpages entries with no slack. The OOB store can land in adjacent slab memory; the bv_len and bv_offset fields written there are derived from client-supplied RPC payload sizes. Move the in-range check ahead of the store in the head, page-loop, and tail branches. With the check at the top of each sequence, count is incremented only after a successful store, so the overflow label can return count directly.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-15

Last Modified

2026-08-17

Generated

2026-09-04

AI Q&A

2026-08-15

EPSS Evaluated

2026-09-03

NVD

CVE-2026-72217

EUVD

EUVD-2026-58975

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This is a buffer overflow vulnerability in the Linux kernel's SUNRPC subsystem. The function xdr_buf_to_bvec() writes data to an array without properly checking if the index is valid first. When the array is exactly full, the next write goes past the end, potentially corrupting adjacent memory. The overflow is masked by returning a reduced count, but the memory corruption still occurs.

Detection Guidance

This vulnerability is specific to the Linux kernel's SUNRPC implementation and requires kernel-level inspection. Detection involves checking kernel versions and SUNRPC-related code paths. Use commands like 'uname -a' to verify kernel version and 'dmesg | grep SUNRPC' to check for related errors. No direct network detection commands are provided in the context.

Impact Analysis

This vulnerability could allow an attacker to corrupt kernel memory by sending specially crafted RPC requests. This might lead to system crashes, privilege escalation, or unauthorized access depending on what memory is overwritten. Systems using NFS or other RPC-based services are most at risk.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It is a low-level memory corruption issue in the Linux kernel's SUNRPC subsystem that could lead to data corruption or crashes but does not inherently violate data protection requirements.

Mitigation Strategies

Apply the latest kernel patches or updates from your Linux distribution to resolve the SUNRPC vulnerability. Monitor vendor advisories for CVE-2026-72217 and update affected systems promptly. Restart services using SUNRPC if required after patching.

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