---
id: CVE-2026-80603
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read

  parse_dcc() treats data_end as an inclusive end pointer, but its only
  caller passes data_limit = ib_pt…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read

  parse_dcc() treats data_end as an inclusive end pointer, but its only
  caller passes data_limit = ib_pt…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'
published: '2026-08-28'
updated: '2026-08-29'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-80603'
references:
  - url: 'https://git.kernel.org/stable/c/2393f0bd7a467ad475598f3a5b9de27ca36e3037'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2b70f61f569bb29acb380e6f616a1bbdee15668f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/437e0a3854b3a44ec15afa9ab88ec215adf3a2fd'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/910c33e4a8c046c3cc1fa5a465a4d41a1bb398f1'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/abb8c32b88ea3f46beb68c34fe9a3ac8ed664e7e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/aff589556ed772cb1c0c2d7b4d91ec45c0c39416'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/eeef3b81f449560653662df2dde6f6fe247c5365'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ef6400ca25a13fd6dedbe8ef4a1d0979bbbfe88a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00595
epssPercentile: 0.46186
ingestedAt: '2026-08-29T22:43:16.073Z'
---

## Overview

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

netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read

parse_dcc() treats data_end as an inclusive end pointer, but its only
caller passes data_limit = ib_ptr + datalen, which points one past the
last valid byte.

The newline search loop iterates while tmp <= data_end, so when no
newline is present, *tmp is read at tmp == data_end, one byte beyond
the region filled by skb_header_pointer().

irc_buffer is kmalloc'd as MAX_SEARCH_SIZE + 1 bytes and datalen is
capped at MAX_SEARCH_SIZE, so the stray read does not fault.  The byte
is uninitialized or stale; if it contains an ASCII digit, simple_strtoul
will consume it and produce a wrong DCC IP or port in the conntrack
expectation.  The extra allocation byte is also a fragile guard: if the
cap or allocation size changes, this becomes a real out-of-bounds read.

Change the loop and its post-loop check to use strict less-than,
consistent with the caller's exclusive-end convention.  Update the
function comment accordingly.

## Remediation

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