Vulnerability · Published Oct 16, 2026 · Assigned by GitHub_M
CVE-2026-48503libIEC61850: Remote information disclosure in MMS file service via out-of-range initialPosition in fileOpen followed by fileRead
High 7.5
In plain English
A high-severity information exposure in libiec61850 from mz-automation. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities).
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| mz-automation | libiec61850 | < 1.6.2 |
Weakness: CWE-191, CWE-200, CWE-252 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N