CVE-2026-48503

7.5High

Published 16 Oct 2026 · NVD status: Deferred · AI triage by gemini-3.8-flash

7.5High

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None
Impact: High impact on confidentiality
Weakness: CWE-191, CWE-200, CWE-252

Impact

Unauthenticated remote attackers can read stale memory buffers containing prior response data and protocol fragments. They only need network access to the MMS file service.

Root cause

The MMS file service accepts an out-of-range initialPosition, causing an unsigned integer underflow during size calculation that leaks reused connection buffer memory.

Affected systems

libIEC61850 prior to 1.6.2

CVSS v3.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Fix & remediation

Upgrade libIEC61850 to version 1.6.2 or later. If updating immediately is not possible, disable the MMS file service in the server configuration.

shell

$ git pull && git checkout v1.6.2 && mkdir build && cd build && cmake .. && make && sudo make install

AI-suggested. Run it in staging first and check it against the vendor advisory. Why?

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NVD 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.

References

Source: nvd.nist.gov/vuln/detail/CVE-2026-48503