Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/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
Pre-auth, low-complexity crash reachable over the network on TCP/102 with no user interaction; impact is availability-only (process termination), so C:N/I:N/A:H.
Primary rating from Vendor (icscert).
CVSS VectorVendor: icscert
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/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
Lifecycle Timeline
6DescriptionCVE.org
The ISO Presentation layer contains a flaw in the handling of specific parameters during normal mode negotiation. A missing length check in the processing of the encoded presentation data allows an attacker controlled field with a zero length value to trigger a bounded heap over read. This condition occurs before MMS session establishment, a crafted TCP/102 connection attempt can trigger the issue. The resulting over read causes the process to terminate, leading to a denial of service condition.
AnalysisAI
Remote unauthenticated denial of service in MZ Automation's libiec61850 (all versions before 1.6.2) allows an attacker to crash IEC 61850/MMS server processes by opening a crafted TCP/102 connection. The flaw sits in the ISO Presentation layer's normal-mode negotiation, where a missing length check on an attacker-controlled zero-length field triggers a bounded heap out-of-bounds read that terminates the process before any MMS session is even established. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires only network TCP reachability to port 102 (ISO-on-TCP/MMS) of a device running libiec61850 prior to 1.6.2 - no authentication, no user interaction, and no non-default feature toggle, since the flaw is hit during standard ISO Presentation normal-mode negotiation that occurs before MMS session establishment. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N, VA:H, VC:N/VI:N) is internally consistent with the description: network-reachable, no authentication, no user interaction, low complexity, and a pure availability impact (denial of service only) with no confidentiality or integrity loss - the score of 8.7 is driven entirely by the ease of remotely crashing the process. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker with network reachability to an exposed IEC 61850 device opens a TCP connection to port 102 and sends a crafted ISO Presentation normal-mode negotiation PDU containing a presentation data field with a zero-length value. The missing length check triggers a heap over-read that terminates the MMS server process before authentication or session setup, dropping the device offline; repeating the connection can sustain a denial-of-service or crash-loop condition. … |
| Remediation | Vendor-released patch: upgrade libiec61850 to version 1.6.2 or later, which adds the missing length check in the ISO Presentation normal-mode negotiation path; downstream device vendors that embed the library must rebuild and redistribute firmware/applications against the fixed version. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Identify and inventory all systems running MZ Automation libiec61850 versions prior to 1.6.2, with priority on Internet-facing or network-accessible IEC 61850/MMS servers. …
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Same weakness CWE-125 – Out-of-bounds Read
View allSame technique Buffer Overflow
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External POC / Exploit Code
Leaving vuln.today
EUVD-2026-51338
GHSA-xhv7-j6rr-ph72