Out-of-bounds Write Affecting kernel6.18-tools-devel package, versions <1:6.18.41-94.142.amzn2023


Severity

Recommended
0.0
high
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.62% (47th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNEL618TOOLSDEVEL-19466233
  • published1 Sept 2026
  • disclosed15 Aug 2026

Introduced: 15 Aug 2026

NewCVE-2026-72217  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.18-tools-devel to version 1:6.18.41-94.142.amzn2023 or higher.
This issue was patched in ALAS2023-2026-2071.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel6.18-tools-devel package and not the kernel6.18-tools-devel package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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 Base Scores

version 3.1