CVE-2026-48503
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.46%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- EPSS
- 0.46% probability · 39th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-191, CWE-200, CWE-252
- Source
- security-advisories@github.com
EPSS moved from 0.5% on 17 October 2026 to 0.5% on 26 October 2026.
References
- https://github.com/mz-automation/libiec61850/commit/bba5bf2fab6d7ac88f5accb4c9e90b123436ebf2
- https://github.com/mz-automation/libiec61850/releases/tag/v1.6.2
- https://github.com/mz-automation/libiec61850/security/advisories/GHSA-4c8m-jr3r-h8j2
- https://github.com/mz-automation/libiec61850/security/advisories/GHSA-4c8m-jr3r-h8j2
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.