---
id: CVE-2026-53151
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  rxrpc: Fix the ACK parser to extract the SACK table for parsing

  Fix modification of the received skbuff in rxrpc_input_soft_acks() and a
  potential incorrect access of …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  rxrpc: Fix the ACK parser to extract the SACK table for parsing

  Fix modification of the received skbuff in rxrpc_input_soft_acks() and a
  potential incorrect access of …
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'
published: '2026-06-25'
updated: '2026-07-04'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53151'
references:
  - url: 'https://git.kernel.org/stable/c/224298450be5c04d2a6ea1c2a94669d7ebf65d00'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/333b6d5bb9f87827ac2639c737bf9613dbae7253'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/566c4c1244de50fbff1f89ff93c9d7b0fc256db4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5d1ae4e17a3ecd8561cdb4f4f70152f41039c4e1'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/775c5e89272a2615b72bb84f611ba66fa3b7493e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00457
epssPercentile: 0.38993
ingestedAt: '2026-07-04T12:56:09.627Z'
---

## Overview

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

rxrpc: Fix the ACK parser to extract the SACK table for parsing

Fix modification of the received skbuff in rxrpc_input_soft_acks() and a
potential incorrect access of the buffer in a fragmented UDP packet (the
packet would probably have to be deliberately pre-generated as fragmented)
when AF_RXRPC tries to extract the contents of the SACK table by copying
out the contents of the SACK table into a buffer before attempting to parse

AF_RXRPC assumes that it can just call skb_condense() and then validly
access the SACK table from skb->data and that it will be a flat buffer -
but skb_condense() can silently fail to do anything under some
circumstances.

Note that whilst rxrpc_input_soft_acks() should be able to parse extended
ACKs, the rest of AF_RXRPC doesn't currently support that.

Further, there's then no need to call skb_condense() in rxrpc_input_ack(),
so don't.

## Remediation

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