---
id: CVE-2026-89526
title: 'svcrdma: Validate Read chunk positions before reconstruction'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  svcrdma: Validate Read chunk positions before reconstruction

  The RPC/RDMA Read chunk position field is supplied by the remote
  client and stored verbatim in the parsed …
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
cwe:
  - CWE-125
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= d96962e6d0e281bab6a48e83b42f5dce6eb28bf4 <
    3861eeabaebe243050952b34063763527c44e1fe
  - >-
    Linux >= d96962e6d0e281bab6a48e83b42f5dce6eb28bf4 <
    5ab3f6d882fe07ae5e61d0bcfeea00b9409155c2
  - >-
    Linux >= d96962e6d0e281bab6a48e83b42f5dce6eb28bf4 <
    f84ec84d8d4bc65f9ae23372570349687f66fa39
  - >-
    Linux >= d96962e6d0e281bab6a48e83b42f5dce6eb28bf4 <
    577097455d084610fc31e91e6a61c5793b6f04ba
  - >-
    Linux >= d96962e6d0e281bab6a48e83b42f5dce6eb28bf4 <
    3779b7b9e7d1c8ba4738f9d327de3b0288cefe9b
  - Linux 5.11
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-16T19:22:57.126783Z'
published: '2026-09-11'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T12:47:39.359Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-89526'
references:
  - url: 'https://git.kernel.org/stable/c/3861eeabaebe243050952b34063763527c44e1fe'
  - url: 'https://git.kernel.org/stable/c/5ab3f6d882fe07ae5e61d0bcfeea00b9409155c2'
  - url: 'https://git.kernel.org/stable/c/f84ec84d8d4bc65f9ae23372570349687f66fa39'
  - url: 'https://git.kernel.org/stable/c/577097455d084610fc31e91e6a61c5793b6f04ba'
  - url: 'https://git.kernel.org/stable/c/3779b7b9e7d1c8ba4738f9d327de3b0288cefe9b'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89526.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89526'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532309'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89526'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89526'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89526.mbox
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00635
epssPercentile: 0.50214
scores:
  cna: 9.8
  vendor: 8.1
ingestedAt: '2026-09-14T15:23:07.475Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

svcrdma: Validate Read chunk positions before reconstruction

The RPC/RDMA Read chunk position field is supplied by the remote
client and stored verbatim in the parsed chunk list.
xdr_count_read_segments() checks only 4-byte alignment; it never
compares the position against the received inline body length.

In the single-chunk path, svc_rdma_read_complete_one() splits the
head and tail kvecs at ch_position. A position past the inline
body underflows the tail length, exposing adjacent slab memory to
the upper XDR decoder.

In the multi-chunk path, svc_rdma_read_multiple_chunks() computes
gap lengths between chunks as unsigned subtractions from
ch_position. Overlapping Read chunks cause these subtractions to
underflow. A final position past the inline body likewise
underflows the trailing gap length. svc_rdma_copy_inline_range()
then copies past the receive buffer into request pages that are
returned to the client through the Reply channel.

Bound inline-range copies in svc_rdma_copy_inline_range() against
the decoded inline RPC body saved in rc_saved_arg. Reject a
single Read chunk positioned beyond that body, and reject
multi-chunk lists where accumulated read bytes exceed the next
chunk's position. Apply the same position and overlap checks in
the call-chunk interleaving path.

## Affected

- `Linux >= d96962e6d0e281bab6a48e83b42f5dce6eb28bf4 < 3861eeabaebe243050952b34063763527c44e1fe`
- `Linux >= d96962e6d0e281bab6a48e83b42f5dce6eb28bf4 < 5ab3f6d882fe07ae5e61d0bcfeea00b9409155c2`
- `Linux >= d96962e6d0e281bab6a48e83b42f5dce6eb28bf4 < f84ec84d8d4bc65f9ae23372570349687f66fa39`
- `Linux >= d96962e6d0e281bab6a48e83b42f5dce6eb28bf4 < 577097455d084610fc31e91e6a61c5793b6f04ba`
- `Linux >= d96962e6d0e281bab6a48e83b42f5dce6eb28bf4 < 3779b7b9e7d1c8ba4738f9d327de3b0288cefe9b`
- `Linux 5.11`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · updated 2026-09-27 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89526.json)