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TI-2026-75344 Aliases CVE-2026-48503

Remote information disclosure in libIEC61850 MMS file service

Priority HIGH 72CWE-191Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-200.

Summary

libIEC61850 before 1.6.2 accepts an out-of-range initialPosition in the MMS file service: fileOpen stores it, and the unsigned subtraction in fileRead underflows (CWE-191). The response is not capped at the bytes read, so it can carry stale data from the reused connection buffer. An unauthenticated remote client can read this data when the file service is enabled.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

libIEC61850 is an open-source implementation of IEC 61850 client and server protocols including MMS, GOOSE, Sampled Values, and R-Session. Prior to 1.6.2, the MMS file service in src/mms/iso_mms/server/mms_file_service.c accepts an out-of-range initialPosition in fileOpen and stores it in the file-read state. The fileRead path then subtracts the larger read position from the file size using unsigned arithmetic and fails to limit the response to the actual FileSystem_readFile return value. The oversized response can include stale bytes from the reused connection buffer after the requested file contents, disclosing prior response data and protocol fragments to an unauthenticated remote client when the file service is enabled. This issue is fixed in version 1.6.2.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00458 39th percentileScored 2026-11-07
Fix Fixed libiec61850 (mz-automation): 1.6.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MZ Automationlibiec61850before 1.6.21.6.2Patch availableCNA
  • libiec61850 VendorMZ Automation Affected before 1.6.2 Fixed in 1.6.2 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:mz-automation:libiec61850:*:*:*:*:*:*:*:*——MZ Automation
  • cpe:2.3:a:mz-automation:libiec61850:*:*:*:*:*:*:*:* Versions — — ·MZ Automation

Remediation

Upgrade libIEC61850 to version 1.6.2, which fixes the issue.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

  • Fix · CNA libiec61850 (mz-automation) Fixed in 1.6.2

Timeline

  1. 2026-10-16 Threatist record created from CVE-2026-48503
  2. 2026-10-16 CISA SSVC decision points changed
  3. 2026-10-16 Priority changed: MEDIUM → HIGH

References

Other 3

  • TI-2026-75355 Infinite loop and out-of-bounds read in libIEC61850 ACSE parsing CVSS 4.0HIGH 8.7
  • TI-2026-75345 Remote NULL dereference in libIEC61850 MMS Read crashes servers CVSS 3.1HIGH 7.5
  • TI-2024-18824 In mz-automation libiec61850 v1.4.0, a NULL Pointer Dereference was detected in the… CVSS 3.1HIGH 7.5
  • TI-2022-05561 Infinite loop in MZ Automation libiec61850 CVSS 3.1HIGH 7.5
  • TI-2026-45011 MZ Automation lib60870 Out-of-bounds Read CVSS 4.0MEDIUM 6.9
  • TI-2026-44285 MZ Automation lib60870 Out-of-bounds Read CVSS 4.0MEDIUM 6.9
See all 64 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences