CVE-2026-92157 in F Prime
Summary
by MITRE • 10/15/2026
F´ (F Prime) is a framework that enables development and deployment of spaceflight and other embedded software applications. Prior to 4.3.0, Svc::FileDownlink SendPartial range validation is vulnerable because unchecked startOffset plus length arithmetic bypasses the range check and stores a wrapped m_endOffset that is inconsistent with m_byteOffset. When an existing source file is larger than a valid startOffset and a SendPartial command supplies a length whose U32 sum with that offset wraps below the file size, under standard F Prime assertion handling, the first data-packet transition reaches FW_ASSERT and aborts or resets the process, causing denial of service. This issue is fixed in version 4.3.0.
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Analysis
by VulDB Data Team • 10/15/2026
F Prime serves as a critical framework for developing and deploying embedded software applications within spaceflight systems and other resource-constrained environments. In versions prior to 4.3.0, the Svc::FileDownlink component contains a significant integer overflow vulnerability rooted in improper range validation during partial file transmission operations. The core technical flaw lies in the arithmetic handling of start offsets and data lengths. Specifically, when processing a SendPartial command, the system calculates an end offset by adding the provided length to the starting byte offset without performing adequate bounds checking on this summation before comparison against the total file size.
This lack of validation allows for integer wraparound conditions typical in unsigned 32-bit arithmetic systems. If an attacker or misconfigured client supplies a startOffset and a length such that their sum exceeds the maximum value representable by a U32, the resulting m_endOffset wraps around to a small positive number. This wrapped value is numerically smaller than the original file size and often inconsistent with the actual memory boundaries intended for access. Consequently, the internal state variables become desynchronized, creating an inconsistency between the logical byte offset tracking (m_byteOffset) and the calculated end boundary (m_endOffset).
The operational impact of this vulnerability manifests primarily as a denial of service against the embedded system running F Prime. Under standard configuration where assertion handling is enabled, the discrepancy detected during the first data-packet transition triggers an FW_ASSERT condition. This assertion failure causes immediate termination or reset of the process responsible for file downlinking. In spaceflight and critical infrastructure contexts, such unexpected resets can lead to loss of telemetry data, interruption of command sequences, and potential destabilization of the host system if recovery mechanisms are not robustly implemented. The vulnerability effectively allows a remote or local actor with access to the FileDownlink interface to disrupt service availability through crafted input parameters that exploit integer overflow behavior.
From a classification perspective, this issue aligns with CWE-190 Integer Overflow or Wraparound and CWE-20 Improper Input Validation within the Common Weakness Enumeration framework. The attack vector relates to ATT&CK technique T1498 Network Denial of Service, as it involves exploiting system resources to cause disruption rather than gaining unauthorized access or data exfiltration in this specific instance. Mitigation strategies primarily involve upgrading to F Prime version 4.3.0 or later, where the arithmetic operations have been corrected with proper range checks that prevent wraparound conditions from occurring during offset calculations. Additionally, developers should implement defensive programming practices such as using safe integer libraries or explicit bounds checking before performing addition on size-related variables to ensure consistency between calculated boundaries and actual resource limits.