GHSA-66Q8-V4RR-393C

Vulnerability from github – Published: 2026-08-28 09:31 – Updated: 2026-08-29 09:30
VLAI
Details

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.

Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
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{
  "affected": [],
  "aliases": [
    "CVE-2026-80603"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-28T08:16:44Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read\n\nparse_dcc() treats data_end as an inclusive end pointer, but its only\ncaller passes data_limit = ib_ptr + datalen, which points one past the\nlast valid byte.\n\nThe newline search loop iterates while tmp \u003c= data_end, so when no\nnewline is present, *tmp is read at tmp == data_end, one byte beyond\nthe region filled by skb_header_pointer().\n\nirc_buffer is kmalloc\u0027d as MAX_SEARCH_SIZE + 1 bytes and datalen is\ncapped at MAX_SEARCH_SIZE, so the stray read does not fault.  The byte\nis uninitialized or stale; if it contains an ASCII digit, simple_strtoul\nwill consume it and produce a wrong DCC IP or port in the conntrack\nexpectation.  The extra allocation byte is also a fragile guard: if the\ncap or allocation size changes, this becomes a real out-of-bounds read.\n\nChange the loop and its post-loop check to use strict less-than,\nconsistent with the caller\u0027s exclusive-end convention.  Update the\nfunction comment accordingly.",
  "id": "GHSA-66q8-v4rr-393c",
  "modified": "2026-08-29T09:30:25Z",
  "published": "2026-08-28T09:31:46Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80603"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2393f0bd7a467ad475598f3a5b9de27ca36e3037"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2b70f61f569bb29acb380e6f616a1bbdee15668f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/437e0a3854b3a44ec15afa9ab88ec215adf3a2fd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/910c33e4a8c046c3cc1fa5a465a4d41a1bb398f1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/abb8c32b88ea3f46beb68c34fe9a3ac8ed664e7e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/aff589556ed772cb1c0c2d7b4d91ec45c0c39416"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/eeef3b81f449560653662df2dde6f6fe247c5365"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ef6400ca25a13fd6dedbe8ef4a1d0979bbbfe88a"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}



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