CVE-2026-80603 (GCVE-0-2026-80603)
Vulnerability from cvelistv5
Published
2026-08-28 06:48
Modified
2026-08-29 06:21
Severity ?
VLAI Severity ?
EPSS score ?
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_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.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/netfilter/nf_conntrack_irc.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
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},
{
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"status": "affected",
"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
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"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
"versionType": "git"
},
{
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"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.12"
},
{
"lessThan": "2.6.12",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.261",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.212",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
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},
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{
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{
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{
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{
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}
],
"negate": false,
"operator": "OR"
}
]
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],
"descriptions": [
{
"lang": "en",
"value": "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."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.1,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - The bug is reached from attacker-controlled TCP payloads on IPv4 flows processed by nf_confirm() (POST_ROUTING/LOCAL_IN) when the IRC conntrack helper is attached, e.g. on an IRC-exposed host or NAT/firewall handling IRC/DCC through netfilter.\nAC:L - Once the IRC helper is active on a tracked flow, exploitation is deterministic: the attacker completes a TCP handshake, sends a crafted client-to-server PRIVMSG/CTCP DCC without a newline at the copy boundary, and can plant the stale byte via the shared global irc_buffer.\nPR:N - No local account or kernel capabilities are required; a remote peer only needs to send network traffic on a connection where the administrator has enabled the IRC helper. Helper configuration is deployment state, not attacker privilege.\nUI:N - No victim-side clicks, mounts, or other interactive actions are needed beyond normal network reachability; the attacker supplies the malicious IRC/DCC payload directly over the established TCP session.\nS:U - Impact is confined to the kernel/netfilter security domain of the affected host (conntrack parsing and expectations). It does not cross VM, IOMMU, or other separate security-authority boundaries.\nC:H - parse_dcc() performs a one-byte out-of-bounds read past skb_header_pointer()\u0027s copied region into stale kmalloc data in the shared irc_buffer, exposing uninitialized or prior-session bytes that can influence subsequent parsing.\nI:H - If the overread byte is an ASCII digit, simple_strtoul() misparses the DCC address/port and can install incorrect nf_conntrack expectations, altering NAT/firewall pinholes rather than only reading memory.\nA:N - The overread is bounded by the deliberately oversized kmalloc guard (MAX_SEARCH_SIZE+1) and the fix commit states the stray access does not fault; this issue does not directly cause kernel oops, panic, or hang."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-29T06:21:14.540Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/abb8c32b88ea3f46beb68c34fe9a3ac8ed664e7e"
},
{
"url": "https://git.kernel.org/stable/c/437e0a3854b3a44ec15afa9ab88ec215adf3a2fd"
},
{
"url": "https://git.kernel.org/stable/c/910c33e4a8c046c3cc1fa5a465a4d41a1bb398f1"
},
{
"url": "https://git.kernel.org/stable/c/2b70f61f569bb29acb380e6f616a1bbdee15668f"
},
{
"url": "https://git.kernel.org/stable/c/2393f0bd7a467ad475598f3a5b9de27ca36e3037"
},
{
"url": "https://git.kernel.org/stable/c/aff589556ed772cb1c0c2d7b4d91ec45c0c39416"
},
{
"url": "https://git.kernel.org/stable/c/eeef3b81f449560653662df2dde6f6fe247c5365"
},
{
"url": "https://git.kernel.org/stable/c/ef6400ca25a13fd6dedbe8ef4a1d0979bbbfe88a"
}
],
"title": "netfilter: nf_conntrack_irc: fix parse_dcc() off-by-one OOB read",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-80603",
"datePublished": "2026-08-28T06:48:29.158Z",
"dateReserved": "2026-08-26T14:34:25.772Z",
"dateUpdated": "2026-08-29T06:21:14.540Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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