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CVE-2026-48503— libIEC61850: Remote information disclosure in MMS file service via out-of-range initialPosition in fileOpen followed by fileRead

Quick assessment

Affected
mz-automation libiec61850
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

libIEC61850 是一个开源的 IEC 61850 客户端与服务器协议实现，涵盖 MMS、GOOSE、采样值（Sampled Values）及 R-Session。在 1.6.2 版本之前，位于 src/mms/iso_mms/server/mms_file_service.c 的 MMS 文件服务在 fileOpen 操作中接受超出范围的 initialPosition 参数，并将其存储到文件读取状态中。随后的 fileRead 路径使用无符号算术运算，将较大的读取位置从文件大小中减去，且未将响应限制在 F

CVSS 7.5 · High
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I. Basic Information for CVE-2026-48503

Vulnerability Information
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Vulnerability Title
libIEC61850: Remote information disclosure in MMS file service via out-of-range initialPosition in fileOpen followed by fileRead
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
mz-automation libiec61850 < 1.6.2 -

II. Public POCs for CVE-2026-48503

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III. Intelligence Information for CVE-2026-48503

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Vendor Pages for CVE-2026-48503 (1)

Other References for CVE-2026-48503 (2)

Same Patch Batch · mz-automation · 2026-10-16 · 6 CVEs total

CVE-2026-68906 8.7 HIGH libIEC61850: Infinite loop and out-of-bounds read in ACSE parseUserInformation when parsin
CVE-2026-68907 8.2 HIGH libIEC61850: Server-side out-of-bounds stack read in association-specific dynamic dataset
CVE-2026-48741 7.5 HIGH libIEC61850: Remote NULL dereference in MMS Read alternate-access sub-array path leads to
CVE-2026-57446 5.3 MEDIUM libIEC61850: Server-side double free in MMS ObtainFile task reuse due to stale FILE* handl
CVE-2026-68908 5.3 MEDIUM libIEC61850: Oversized RptID can trigger invalid free of a stack-backed visible string in

IV. Related Vulnerabilities

Same product: libiec61850
Same vendor: mz-automation
Same weakness: CWE-191

V. Comments for CVE-2026-48503

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