CVE-2026-68907 in libiec61850
Summary
by MITRE • 10/16/2026
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, checkDataSetAccess reverses the source and destination arguments to StringUtils_copyStringToBuffer while constructing an MMS_ASSOCIATION_SPECIFIC dataset reference. The helper treats uninitialized dataSetRef[130] storage as a source string, causing strlen to read beyond the stack buffer, and then copies those bytes into the caller-owned listName buffer. A remote defineNamedVariableList request can crash servers that have dynamic dataset service enabled and a dataset access handler installed; the advisory also observes caller stack corruption but establishes denial of service as the primary impact. This issue is fixed in version 1.6.2.
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Analysis
by VulDB Data Team • 10/16/2026
The vulnerability identified in libIEC61850 versions prior to 1.6.2 represents a critical memory safety flaw within the implementation of the IEC 61850 protocol stack, specifically affecting the MMS (Manufacturing Message Specification) layer used for client-server communication in industrial automation systems. The core technical defect resides in the checkDataSetAccess function, which is responsible for validating access rights to datasets before processing requests. During the construction of an MMS_ASSOCIATION_SPECIFIC dataset reference, this function incorrectly reverses the source and destination arguments when invoking the StringUtils_copyStringToBuffer helper routine. This argument swap fundamentally alters the data flow logic intended by the developers, leading to a severe out-of-bounds read condition that compromises both confidentiality and availability within the affected system components.
The operational mechanism of this flaw begins with the declaration of an uninitialized local array named dataSetRef[130] on the stack. Due to the reversed arguments in the copy function call, the helper routine treats this uninitialized buffer as the source string rather than the destination. Consequently, the strlen function is executed against this garbage data to determine its length for copying purposes. Because the memory region contains undefined values from previous stack operations or random noise, strlen continues reading beyond the boundaries of the allocated 130-byte array until it encounters a null terminator somewhere in adjacent memory. This results in an out-of-bounds read that accesses arbitrary portions of the process's virtual address space, potentially exposing sensitive internal state information to remote attackers who can trigger this code path through network traffic.
Following the erroneous length calculation, the vulnerable copy operation proceeds to write data into the caller-owned listName buffer based on the inflated size derived from the out-of-bounds read. While the advisory notes that stack corruption is a possible outcome due to these improper memory operations, the primary and most reliably exploitable impact observed is denial of service. When a remote attacker sends a specifically crafted defineNamedVariableList request targeting systems with dynamic dataset services enabled and an installed dataset access handler, the resulting invalid memory access triggers undefined behavior within the server process. In practice, this manifests as immediate application crashes or segmentation faults, effectively taking down critical industrial control system components that rely on continuous availability for real-time monitoring and control operations.
From a classification perspective, this vulnerability aligns with CWE-125 Out-of-bounds Read, which describes reading data outside of the intended buffer boundaries, often leading to information disclosure or application crashes depending on the context. Furthermore, given its location within an IEC 61850 server component and its ability to disrupt service availability through remote network requests, it maps directly to MITRE ATT&CK technique T1499 Endpoint Denial of Service under the Impact tactic. The vulnerability highlights a common class of errors in C-based protocol implementations where manual memory management is coupled with insufficient input validation or logical errors in function parameter ordering, underscoring the risks associated with legacy codebases that may lack modern static analysis protections against such logic flaws.
Mitigation for this issue requires immediate upgrading to libIEC61850 version 1.6.2 or later, where the argument order in checkDataSetAccess has been corrected and proper bounds checking is implemented before string operations are performed on stack-allocated buffers. For environments where an upgrade is not immediately feasible, network-level mitigations should be considered, such as restricting access to IEC 61850 MMS ports using firewalls or intrusion prevention systems configured to detect anomalous defineNamedVariableList payloads with unusually large lengths indicative of the out-of-bounds read condition. Additionally, enabling core dump analysis and logging can help in identifying potential exploitation attempts by monitoring for sudden process terminations associated with dataset access handlers, although these measures are reactive rather than preventive compared to applying the vendor-provided patch.