CVE-2026-48503: CWE-191: Integer Underflow (Wrap or Wraparound) in mz-automation libiec61850
Description
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.
CVSS v3.1
Score 7.5high
Affected software
mz-automation
libiec61850
pkg:github/mz-automation/libiec61850Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in libIEC61850's MMS file service arises from accepting an out-of-range initialPosition in fileOpen, which is stored in the file-read state. During fileRead, unsigned arithmetic subtracts this larger read position from the file size without proper bounds checking, resulting in an oversized response. This oversized response can include stale data from reused connection buffers, leading to information disclosure of prior response data and protocol fragments to unauthenticated remote clients. The flaw is classified as an integer underflow (CWE-191) and leads to information exposure (CWE-200) due to improper handling of file read boundaries. The issue is resolved in libiec61850 version 1.6.2.
Potential Impact
An unauthenticated remote attacker can exploit this vulnerability to receive stale data from previous file service responses, potentially disclosing sensitive information or protocol fragments. The vulnerability does not affect integrity or availability but results in a confidentiality breach. The CVSS 3.1 base score is 7.5 (high severity), reflecting network attack vector, low attack complexity, no privileges required, no user interaction, and high confidentiality impact.
Mitigation Recommendations
Upgrade libiec61850 to version 1.6.2 or later, where this vulnerability is fixed. No other mitigations are specified or required once the official fix is applied.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-21T15:33:08.293Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ad24b622cdf04f656070138
Added to database: 10/16/2026, 16:05:54 UTC
Last enriched: 10/16/2026, 16:18:30 UTC
Last updated: 10/16/2026, 19:03:29 UTC
Views: 10
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