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Fencer Vulns
high 7.5

CVE-2026-48503 json

libIEC61850: Remote information disclosure in MMS file service via out-of-range initialPosition in fileOpen followed by fileRead

published 2026-10-16 23 d ago modified 2026-10-16 23 d ago also EUVD-2026-102907

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 39%
public exploits
0
none known

Summary

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.

Patch / fix

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
23 d ago

Exploit prediction

0.46% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/mz-automation/libiec61850/security/advisories/GHSA-4c8m-jr3r-h8j2 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

  • mz-automation libiec61850

Classification

Weakness
  • CWE-191 Integer Underflow (Wrap or Wraparound)
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-252 Unchecked Return Value

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.