CVE-2026-56099
Full vulnerability record from the local CVENow database.
Description
OpenBSD before commit 6a23123 (2026-06-18) contains an out-of-bounds read vulnerability in the mpls_do_error function within sys/netmpls/mpls_input.c that allows remote attackers to disclose kernel stack memory by sending crafted MPLS frames with 16 labels and no Bottom-of-Stack bit set.
Severity
MEDIUM
CVSS score
6.9
(v4.0)
Vulnerability status
Analyzed
Source identifier
Published
2026-06-18 20:16:15.370000
Last modified
2026-10-26 11:10:00.157000
View original CVE JSON
{
"id": "CVE-2026-56099",
"sourceIdentifier": "[email protected]",
"published": "2026-06-18T20:16:15.370",
"lastModified": "2026-10-26T11:10:00.157",
"vulnStatus": "Analyzed",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "OpenBSD before commit 6a23123 (2026-06-18) contains an out-of-bounds read vulnerability in the mpls_do_error function within sys/netmpls/mpls_input.c that allows remote attackers to disclose kernel stack memory by sending crafted MPLS frames with 16 labels and no Bottom-of-Stack bit set."
},
{
"lang": "es",
"value": "OpenBSD antes del commit 6a23123 (18-06-2026) contiene una vulnerabilidad de lectura fuera de límites en la función mpls_do_error dentro de sys/netmpls/mpls_input.c que permite a atacantes remotos divulgar memoria de la pila del kernel mediante el envío de tramas MPLS manipuladas con 16 etiquetas y sin el bit Bottom-of-Stack establecido."
}
],
"affected": [
{
"source": "[email protected]",
"affectedData": [
{
"vendor": "openbsd",
"product": "src",
"defaultStatus": "affected",
"repo": "https://github.com/openbsd/src",
"packageURL": "pkg:github/openbsd/src",
"versions": [
{
"version": "0",
"lessThan": "6a23123ec05f1eb29cfcaae0f3a468b2e1983cfd",
"versionType": "git",
"status": "affected"
}
]
}
]
}
],
"metrics": {
"cvssMetricV40": [
{
"source": "[email protected]",
"type": "Secondary",
"cvssData": {
"version": "4.0",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"baseScore": 6.9,
"baseSeverity": "MEDIUM",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"vulnConfidentialityImpact": "LOW",
"vulnIntegrityImpact": "NONE",
"vulnAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"subAvailabilityImpact": "NONE",
"exploitMaturity": "NOT_DEFINED",
"confidentialityRequirement": "NOT_DEFINED",
"integrityRequirement": "NOT_DEFINED",
"availabilityRequirement": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnIntegrityImpact": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"valueDensity": "NOT_DEFINED",
"vulnerabilityResponseEffort": "NOT_DEFINED",
"providerUrgency": "NOT_DEFINED"
}
}
],
"cvssMetricV31": [
{
"source": "[email protected]",
"type": "Secondary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"availabilityImpact": "NONE"
},
"exploitabilityScore": 3.9,
"impactScore": 1.4
},
{
"source": "[email protected]",
"type": "Primary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"availabilityImpact": "NONE"
},
"exploitabilityScore": 3.9,
"impactScore": 1.4
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"timestamp": "2026-06-23T20:44:12.654787Z",
"id": "CVE-2026-56099",
"options": [
{
"exploitation": "none"
},
{
"automatable": "yes"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
]
},
"weaknesses": [
{
"source": "[email protected]",
"type": "Secondary",
"description": [
{
"lang": "en",
"value": "CWE-125"
}
]
}
],
"configurations": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
{
"vulnerable": true,
"criteria": "cpe:2.3:o:openbsd:openbsd:*:*:*:*:*:*:*:*",
"versionEndExcluding": "2026-06-18",
"matchCriteriaId": "4ABC1C39-6D02-4595-AF9A-C6EEA12CE451"
}
]
}
]
}
],
"references": [
{
"url": "https://github.com/openbsd/src/commit/6a23123ec05f1eb29cfcaae0f3a468b2e1983cfd",
"source": "[email protected]",
"tags": [
"Patch"
]
},
{
"url": "https://pop.argus-systems.ai/advisory/adv-040.html",
"source": "[email protected]",
"tags": [
"Exploit",
"Patch",
"Third Party Advisory"
]
},
{
"url": "https://www.vulncheck.com/advisories/openbsd-mpls-do-error-kernel-stack-memory-disclosure-via-mpls-input",
"source": "[email protected]",
"tags": [
"Third Party Advisory"
]
},
{
"url": "http://seclists.org/fulldisclosure/2026/Jun/17",
"source": "af854a3a-2127-422b-91ae-364da2661108",
"tags": [
"Exploit",
"Mailing List",
"Patch",
"Third Party Advisory"
]
},
{
"url": "http://www.openwall.com/lists/oss-security/2026/06/19/3",
"source": "af854a3a-2127-422b-91ae-364da2661108",
"tags": [
"Exploit",
"Mailing List",
"Patch",
"Third Party Advisory"
]
}
]
}