CVE-2026-80586 (GCVE-0-2026-80586)
Vulnerability from cvelistv5 – Published: 2026-08-26 14:37 – Updated: 2026-08-27 05:02
VLAI
EPSS
VEX
Title
mptcp: options: reset DSS fields in case of unexpected size
Summary
In the Linux kernel, the following vulnerability has been resolved:
mptcp: options: reset DSS fields in case of unexpected size
A remote peer could send a malformed DSS with a wrong size, followed by
another DSS or MPC + Data. In this case, the first suboption will be
ignored, but leaving some fields written, which could lead to
inconsistency or access uninitialized data.
Explicitly reset the fields that could have been modified in case of
unexpected size.
Severity
9.8 (Critical)
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
648ef4b88673dadb8463bf0d4b10fbf33d55def8 , < 15e35fdad7a5576bf3f1c8d688877aeb5d1b506b
(git)
Affected: 648ef4b88673dadb8463bf0d4b10fbf33d55def8 , < b1256090816ec46011601e084be580731df58fc7 (git) Affected: 648ef4b88673dadb8463bf0d4b10fbf33d55def8 , < 192878df582c51d440bf7b91a15f297f29f2b596 (git) Affected: 648ef4b88673dadb8463bf0d4b10fbf33d55def8 , < 26dac5c9ffb20812b475fdf253eb04fab99cff3b (git) Affected: 648ef4b88673dadb8463bf0d4b10fbf33d55def8 , < 4e80eff5c1c893aca2ac1d202f0b256d2e52ecde (git) Affected: 648ef4b88673dadb8463bf0d4b10fbf33d55def8 , < 1fade1b2ac5b1a4948e538fae7313bea57b5ac36 (git) Affected: 648ef4b88673dadb8463bf0d4b10fbf33d55def8 , < 27ed642a4e7e4b5df4b8522c72c457a67e052493 (git) Affected: 648ef4b88673dadb8463bf0d4b10fbf33d55def8 , < 35772b4981f38ba8059372cde8753e8e477e98ec (git) |
guessed | |
| Linux | Linux |
Affected:
5.6
Unaffected: 0 , < 5.6 (semver) Unaffected: 5.10.266 , ≤ 5.10.* (semver) Unaffected: 5.15.217 , ≤ 5.15.* (semver) Unaffected: 6.1.184 , ≤ 6.1.* (semver) Unaffected: 6.6.153 , ≤ 6.6.* (semver) Unaffected: 6.12.105 , ≤ 6.12.* (semver) Unaffected: 6.18.46 , ≤ 6.18.* (semver) Unaffected: 7.1.10 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/mptcp/options.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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},
{
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"versionType": "git"
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"status": "affected",
"version": "648ef4b88673dadb8463bf0d4b10fbf33d55def8",
"versionType": "git"
},
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"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/mptcp/options.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.6"
},
{
"lessThan": "5.6",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.266",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.217",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.184",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.153",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.105",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.46",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.10",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.266",
"versionStartIncluding": "5.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.217",
"versionStartIncluding": "5.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.184",
"versionStartIncluding": "5.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.153",
"versionStartIncluding": "5.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.105",
"versionStartIncluding": "5.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.46",
"versionStartIncluding": "5.6",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.10",
"versionStartIncluding": "5.6",
"vulnerable": true
},
{
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"versionEndExcluding": "7.2",
"versionStartIncluding": "5.6",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: options: reset DSS fields in case of unexpected size\n\nA remote peer could send a malformed DSS with a wrong size, followed by\nanother DSS or MPC + Data. In this case, the first suboption will be\nignored, but leaving some fields written, which could lead to\ninconsistency or access uninitialized data.\n\nExplicitly reset the fields that could have been modified in case of\nunexpected size."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - Remote attacker sends crafted TCP segments with malformed MPTCP options that are parsed in the softirq receive path (tcp_v4_rcv/tcp_rcv_established/tcp_data_queue/mptcp_incoming_options/mptcp_get_options), requiring only network reachability to an MPTCP-enabled peer.\nAC:L - Attacker fully controls TCP option bytes on an established MPTCP connection and can deterministically send a size-invalid DSS (setting use_ack/use_map flags) immediately followed by MPC+Data or another DSS in the same header; no race or victim-specific state is required.\nPR:N - Only requires the attacker to be the remote MPTCP/TCP peer of a host with CONFIG_MPTCP enabled; no local account, capabilities, or authenticated access on the victim is needed to reach the vulnerable parser.\nUI:N - Exploitation is fully automated over the network once an MPTCP session exists; the kernel processes malicious segments in softirq without any victim user action beyond ordinary connectivity.\nS:U - Impact is limited to kernel networking/MPTCP connection state on the affected host and does not cross VM, container, or IOMMU security boundaries.\nC:H - Malformed DSS leaves use_ack/use_map/dsn64/data_fin set while data_ack and map fields are never read, so ack_update_msk() and DSS handling consume uninitialized stack values and corrupt metadata that can leak kernel memory contents.\nI:H - Stale DSS flag bits cause forged ack advancement of msk-\u003esnd_una/wnd_end/bytes_acked and bogus DATA_FIN/DSN mapping in skb extensions, corrupting rtx queues and silently altering or truncating application data delivery.\nA:H - Bogus ack state triggers __mptcp_clean_una() WARN_ON_ONCE paths outside recovery, can abort or hang MPTCP connections, and may kernel-panic systems built with panic_on_warn."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-27T05:02:07.204Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/15e35fdad7a5576bf3f1c8d688877aeb5d1b506b"
},
{
"url": "https://git.kernel.org/stable/c/b1256090816ec46011601e084be580731df58fc7"
},
{
"url": "https://git.kernel.org/stable/c/192878df582c51d440bf7b91a15f297f29f2b596"
},
{
"url": "https://git.kernel.org/stable/c/26dac5c9ffb20812b475fdf253eb04fab99cff3b"
},
{
"url": "https://git.kernel.org/stable/c/4e80eff5c1c893aca2ac1d202f0b256d2e52ecde"
},
{
"url": "https://git.kernel.org/stable/c/1fade1b2ac5b1a4948e538fae7313bea57b5ac36"
},
{
"url": "https://git.kernel.org/stable/c/27ed642a4e7e4b5df4b8522c72c457a67e052493"
},
{
"url": "https://git.kernel.org/stable/c/35772b4981f38ba8059372cde8753e8e477e98ec"
}
],
"title": "mptcp: options: reset DSS fields in case of unexpected size",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-80586",
"datePublished": "2026-08-26T14:37:41.493Z",
"dateReserved": "2026-08-26T14:34:25.769Z",
"dateUpdated": "2026-08-27T05:02:07.204Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-80586",
"date": "2026-08-27",
"epss": "0.00404",
"percentile": "0.33415"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2026-80586\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-26T15:17:14.873\",\"lastModified\":\"2026-08-27T06:17:45.700\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nmptcp: options: reset DSS fields in case of unexpected size\\n\\nA remote peer could send a malformed DSS with a wrong size, followed by\\nanother DSS or MPC + Data. In this case, the first suboption will be\\nignored, but leaving some fields written, which could lead to\\ninconsistency or access uninitialized data.\\n\\nExplicitly reset the fields that could have been modified in case of\\nunexpected size.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/mptcp/options.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"648ef4b88673dadb8463bf0d4b10fbf33d55def8\",\"lessThan\":\"15e35fdad7a5576bf3f1c8d688877aeb5d1b506b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"648ef4b88673dadb8463bf0d4b10fbf33d55def8\",\"lessThan\":\"b1256090816ec46011601e084be580731df58fc7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"648ef4b88673dadb8463bf0d4b10fbf33d55def8\",\"lessThan\":\"192878df582c51d440bf7b91a15f297f29f2b596\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"648ef4b88673dadb8463bf0d4b10fbf33d55def8\",\"lessThan\":\"26dac5c9ffb20812b475fdf253eb04fab99cff3b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"648ef4b88673dadb8463bf0d4b10fbf33d55def8\",\"lessThan\":\"4e80eff5c1c893aca2ac1d202f0b256d2e52ecde\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"648ef4b88673dadb8463bf0d4b10fbf33d55def8\",\"lessThan\":\"1fade1b2ac5b1a4948e538fae7313bea57b5ac36\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"648ef4b88673dadb8463bf0d4b10fbf33d55def8\",\"lessThan\":\"27ed642a4e7e4b5df4b8522c72c457a67e052493\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"648ef4b88673dadb8463bf0d4b10fbf33d55def8\",\"lessThan\":\"35772b4981f38ba8059372cde8753e8e477e98ec\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/mptcp/options.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.6\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.6\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.266\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.217\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.184\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.153\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.105\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.46\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.10\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/15e35fdad7a5576bf3f1c8d688877aeb5d1b506b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/192878df582c51d440bf7b91a15f297f29f2b596\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/1fade1b2ac5b1a4948e538fae7313bea57b5ac36\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/26dac5c9ffb20812b475fdf253eb04fab99cff3b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/27ed642a4e7e4b5df4b8522c72c457a67e052493\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/35772b4981f38ba8059372cde8753e8e477e98ec\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/4e80eff5c1c893aca2ac1d202f0b256d2e52ecde\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b1256090816ec46011601e084be580731df58fc7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
"redhat_vex": {
"aggregate_severity": "Important",
"current_release_date": "2026-08-27T07:51:58+00:00",
"cve": "CVE-2026-80586",
"id": "CVE-2026-80586",
"initial_release_date": "2026-08-26T00:00:00+00:00",
"product_status:known_affected": "232",
"product_status:known_not_affected": "42",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: mptcp: options: reset DSS fields in case of unexpected size",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80586.json",
"version": "3"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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