CVE-2026-66349 (GCVE-0-2026-66349)
Vulnerability from cvelistv5 – Published: 2026-07-30 22:31 – Updated: 2026-07-30 22:31
VLAI
EPSS
VEX
Title
MZ Automation libiec61850 Out-of-bounds Read
Summary
The MMS server connection handler contains a flaw in its processing of
BER-encoded request data. When an MMS confirmed request PDU containing
an extended BER tag is received over an established session, the decoder
may advance its internal buffer incorrectly due to a missing bounds
check. This results in a one byte heap out-of-bounds read and causes the
MMS service process to terminate, leading to a denial-of-service
condition.
Severity
6.5 (Medium)
CWE
Assigner
References
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| MZ Automation GmbH | libiec61850 |
Affected:
0 , < 1.6.2
(custom)
Unaffected: 1.6.2 |
Credits
{
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"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "libiec61850",
"vendor": "MZ Automation GmbH",
"versions": [
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"status": "affected",
"version": "0",
"versionType": "custom"
},
{
"status": "unaffected",
"version": "1.6.2"
}
]
}
],
"credits": [
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"lang": "en",
"type": "finder",
"value": "Arun Babu of Central Power Research Institute reported this vulnerability to CISA."
}
],
"descriptions": [
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"value": "The MMS server connection handler contains a flaw in its processing of \nBER-encoded request data. When an MMS confirmed request PDU containing \nan extended BER tag is received over an established session, the decoder\n may advance its internal buffer incorrectly due to a missing bounds \ncheck. This results in a one byte heap out-of-bounds read and causes the\n MMS service process to terminate, leading to a denial-of-service \ncondition."
}
],
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}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "ADJACENT_NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 6.5,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
},
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "NONE",
"attackVector": "ADJACENT",
"baseScore": 6.9,
"baseSeverity": "MEDIUM",
"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "LOW",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-125",
"description": "CWE-125",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-07-30T22:31:32.618Z",
"orgId": "7d14cffa-0d7d-4270-9dc0-52cabd5a23a6",
"shortName": "icscert"
},
"references": [
{
"url": "https://www.cisa.gov/news-events/ics-advisories/icsa-26-211-10"
},
{
"url": "https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-211-10.json"
}
],
"solutions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "MZ Automation GmbH recommends that users update to version 1.6.2."
}
],
"value": "MZ Automation GmbH recommends that users update to version 1.6.2."
}
],
"source": {
"advisory": "ICSA-26-211-10",
"discovery": "EXTERNAL"
},
"title": "MZ Automation libiec61850 Out-of-bounds Read",
"x_generator": {
"engine": "Vulnogram 1.0.4"
}
}
},
"cveMetadata": {
"assignerOrgId": "7d14cffa-0d7d-4270-9dc0-52cabd5a23a6",
"assignerShortName": "icscert",
"cveId": "CVE-2026-66349",
"datePublished": "2026-07-30T22:31:32.618Z",
"dateReserved": "2026-07-27T19:32:49.401Z",
"dateUpdated": "2026-07-30T22:31:32.618Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2026-66349\",\"sourceIdentifier\":\"ics-cert@hq.dhs.gov\",\"published\":\"2026-07-30T23:16:52.920\",\"lastModified\":\"2026-07-30T23:16:52.920\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"The MMS server connection handler contains a flaw in its processing of \\nBER-encoded request data. When an MMS confirmed request PDU containing \\nan extended BER tag is received over an established session, the decoder\\n may advance its internal buffer incorrectly due to a missing bounds \\ncheck. This results in a one byte heap out-of-bounds read and causes the\\n MMS service process to terminate, leading to a denial-of-service \\ncondition.\"}],\"affected\":[{\"source\":\"ics-cert@hq.dhs.gov\",\"affectedData\":[{\"vendor\":\"MZ Automation GmbH\",\"product\":\"libiec61850\",\"defaultStatus\":\"unaffected\",\"versions\":[{\"version\":\"0\",\"lessThan\":\"1.6.2\",\"versionType\":\"custom\",\"status\":\"affected\"},{\"version\":\"1.6.2\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"ics-cert@hq.dhs.gov\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/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\":\"ADJACENT\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"HIGH\",\"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\":\"ics-cert@hq.dhs.gov\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":6.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"ADJACENT_NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"ics-cert@hq.dhs.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-125\"}]}],\"references\":[{\"url\":\"https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-211-10.json\",\"source\":\"ics-cert@hq.dhs.gov\"},{\"url\":\"https://www.cisa.gov/news-events/ics-advisories/icsa-26-211-10\",\"source\":\"ics-cert@hq.dhs.gov\"}]}}"
}
}
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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.
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