CVE-2026-67977 Overview
CVE-2026-67977 is an integer overflow vulnerability in the Svc::FileDownlink::SendPartial component of the NASA F´ (fprime) flight software framework version 4.2.2. Attackers can send crafted input to trigger the overflow and cause a Denial of Service (DoS) condition. The flaw is network-accessible, requires no privileges, and no user interaction. F´ is an open-source component-based framework used to develop flight software for spacecraft and embedded systems, making resilience against DoS conditions important for mission-critical deployments. The weakness is classified under CWE-400 (Uncontrolled Resource Consumption).
Critical Impact
Remote attackers can crash or destabilize fprime-based systems by sending a crafted partial file downlink request, disrupting availability of flight software services.
Affected Products
- NASA F´ (fprime) framework version 4.2.2
- The Svc::FileDownlink::SendPartial component
- Downstream flight software builds embedding the affected fprime release
Discovery Timeline
- 2026-08-03 - CVE-2026-67977 published to NVD
- 2026-08-05 - Last updated in NVD database
Technical Details for CVE-2026-67977
Vulnerability Analysis
The Svc::FileDownlink service in fprime enables ground systems to request file transfers from a spacecraft or embedded target. The SendPartial operation accepts parameters that specify a byte offset and length within a file to transmit. An integer overflow occurs when attacker-controlled numeric inputs are combined arithmetically without bounds validation, producing a wrapped value that violates internal invariants. The resulting condition causes the component to fault, halt, or otherwise disrupt normal file downlink processing. Because F´ services often run on constrained embedded targets, service disruption can cascade into wider mission or subsystem unavailability.
Root Cause
The root cause is uncontrolled arithmetic on untrusted input inside Svc::FileDownlink::SendPartial. Offset and length values are used in size or address computations without validating that their sum stays within the declared file size and integer type range. This maps to CWE-400, where the framework does not adequately constrain resource-related parameters supplied by remote callers.
Attack Vector
An attacker who can reach the fprime command and data handling interface issues a crafted SendPartial request with boundary-case offset and length values. No authentication or user interaction is required for the exploit path described in the advisory. Successful exploitation results in a Denial of Service against the file downlink component and potentially the hosting fprime deployment. Additional technical context is available in the GitHub Issue Tracker and the NASA F´ Prime Project.
No verified proof-of-concept code is published in the referenced sources; the vulnerability manifests through arithmetic wraparound in the SendPartial parameter handling path. Consult the linked issue tracker for reproduction details.
Detection Methods for CVE-2026-67977
Indicators of Compromise
- Unexpected crashes, restarts, or watchdog resets of processes hosting the fprime Svc::FileDownlink component.
- File downlink requests containing extreme offset or length values, or values whose sum exceeds the target file size or U32 range.
- Repeated malformed SendPartial commands from a single ground-station source or network peer.
Detection Strategies
- Instrument the FileDownlink component to log rejected or out-of-range SendPartial parameters and alert on abnormal frequency.
- Correlate ground command telemetry with process health events to identify DoS attempts that precede a service fault.
- Add fuzz testing coverage against SendPartial parameter boundaries in continuous integration pipelines before deployment.
Monitoring Recommendations
- Monitor availability metrics for the file downlink service and alert on service restarts or exception counters.
- Capture command receipt logs at the ground-to-flight interface and retain them for post-incident analysis.
- Track network exposure of fprime command endpoints and restrict which peers can send file transfer commands.
How to Mitigate CVE-2026-67977
Immediate Actions Required
- Inventory all systems running fprime v4.2.2 and identify those exposing the FileDownlink service to untrusted networks.
- Restrict command interface access to authenticated, allow-listed ground stations or internal networks only.
- Apply input validation at the component boundary, rejecting SendPartial requests where offset plus length exceeds the file size or overflows the integer type.
Patch Information
At the time of publication, no fixed release is referenced in the NVD entry. Track the NASA F´ Prime Project repository and the GitHub Issue Tracker for upstream patches addressing the Svc::FileDownlink::SendPartial integer overflow, and upgrade beyond v4.2.2 once a fixed version is released.
Workarounds
- Add a wrapper or guard around SendPartial that validates offset and length as U64 before casting, and rejects any request where the sum overflows or exceeds file size.
- Rate-limit inbound file downlink commands and drop malformed frames at the uplink handler.
- Disable the FileDownlink component in builds that do not require partial file transfer functionality.
# Example allow-list restriction on the fprime command uplink socket
# Replace <ground_station_ip> and <uplink_port> with deployment values
iptables -A INPUT -p tcp --dport <uplink_port> -s <ground_station_ip> -j ACCEPT
iptables -A INPUT -p tcp --dport <uplink_port> -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
