CVE-2026-49035Public exploitNetwork attack vector

Unauthenticated server crash via MMS size underflow

Published Jul 23, 2026 · Updated Jul 23, 2026

Heap-based buffer overflow in libIEC61850 1.0.0 through 1.6.1 allows remote attackers to crash MMS servers via a crafted Initiate request. mms_file_service.c subtracts 20 from an unchecked client maxPduSize; values below 20 underflow maxFileChunkSize and let FileRead copy a staged file into a fixed 65,100-byte heap buffer. Default servers require no credentials, but code execution was demonstrated only with ASLR disabled and a non-PIE build; hardened builds still crash when the file service is reachable and a large file is available.

CVSS severity9.2
Critical
EPSS probability0.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in libIEC61850 1.0.0 through 1.6.1 allows remote attackers to crash MMS servers via a crafted Initiate request. mms_file_service.c subtracts 20 from an unchecked client maxPduSize; values below 20 underflow maxFileChunkSize and let FileRead copy a staged file into a fixed 65,100-byte heap buffer. Default servers require no credentials, but code execution was demonstrated only with ASLR disabled and a non-PIE build; hardened builds still crash when the file service is reachable and a large file is available.

The record

CVE
CVE-2026-49035
Published
Jul 23, 2026
Updated
Jul 23, 2026
Vendor
MZ Automation GmbH
Product
libIEC61850
Classifications
CWE-122, T1499.004, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0.0 <=1.6.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MZ Automation GmbH · libIEC61850version=1.0.0 <=1.6.1

Published CVSS scores

8.1CISA ICS-CERTCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
9.2CISA ICS-CERTCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
T1499.004Application or System Exploitation Flood
T1210Exploitation of Remote Services

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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