CVE-2026-5475: NASA cFS Buffer Overflow Vulnerability

CVE-2026-5475 Overview

A memory corruption vulnerability has been identified in NASA core Flight System (cFS) affecting versions up to 7.0.0. This vulnerability impacts the CFE_SB_TransmitMsg function within the cfe_sb_priv.c file, specifically in the CCSDS Header Size Handler component. An attacker capable of manipulating data through this component can trigger memory corruption conditions.

Critical Impact
Memory corruption in flight software systems can lead to unpredictable behavior, potential denial of service, or compromise of spacecraft command and telemetry systems.

Affected Products

NASA cFS (core Flight System) versions up to 7.0.0
cfe_sb_priv.c component - CCSDS Header Size Handler
Systems implementing CFE_SB_TransmitMsg function

Discovery Timeline

2026-04-03 - CVE-2026-5475 published to NVD
2026-04-07 - Last updated in NVD database

Technical Details for CVE-2026-5475

Vulnerability Analysis

This vulnerability falls under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the Software Bus (SB) message transmission functionality of NASA's core Flight System, a reusable software framework designed for spacecraft flight software applications.

The affected function CFE_SB_TransmitMsg handles CCSDS (Consultative Committee for Space Data Systems) packet headers, which are standard protocols used in space communications. When processing malformed or specially crafted CCSDS header size values, the function fails to properly validate memory boundaries, potentially leading to out-of-bounds memory operations.

The vulnerability requires adjacent network access and low-privilege authentication, limiting the attack surface to threat actors with local network presence within the spacecraft's software environment or ground control systems with direct communication capabilities.

Root Cause

The root cause stems from improper bounds checking in the CCSDS Header Size Handler when processing message transmissions through the Software Bus. The CFE_SB_TransmitMsg function does not adequately validate header size parameters before performing memory operations, creating conditions where memory corruption can occur through crafted input manipulation.

Attack Vector

The attack requires adjacent network access (AV:A), meaning the attacker must have access to the local network segment where the cFS instance operates. This could include:

Ground control station networks with direct communication links
Development or testing environments running cFS instances
Networked simulation environments

Exploitation involves crafting malicious CCSDS packets with manipulated header size values that, when processed by the vulnerable CFE_SB_TransmitMsg function, cause the system to perform memory operations outside intended buffer boundaries. The low attack complexity and no user interaction requirement indicate that once network adjacency is achieved, exploitation is straightforward.

The vulnerability mechanism involves improper handling of CCSDS header size values in the message transmission path. When the CFE_SB_TransmitMsg function processes messages with unexpected header dimensions, memory corruption can occur due to insufficient boundary validation. Technical details and the original issue report are available via GitHub cFS Issue #953.

Detection Methods for CVE-2026-5475

Indicators of Compromise

Unexpected crashes or restarts of cFS application processes
Abnormal memory allocation patterns in Software Bus components
CCSDS packets with malformed or unusual header size values in telemetry logs
Memory access violations or segmentation faults in cfe_sb_priv.c related functions

Detection Strategies

Implement memory integrity monitoring for cFS processes to detect corruption events
Deploy network traffic analysis to identify malformed CCSDS packets with anomalous header sizes
Enable verbose logging for Software Bus message transmission operations
Utilize static code analysis tools to identify similar boundary condition issues in custom cFS modules

Monitoring Recommendations

Monitor system logs for memory-related errors in the CFE_SB subsystem
Implement runtime memory protection mechanisms where supported by the target platform
Establish baseline metrics for normal Software Bus message patterns to detect anomalies
Review ground system network traffic for unexpected CCSDS packet structures

How to Mitigate CVE-2026-5475

Immediate Actions Required

Audit all cFS deployments to identify instances running affected versions up to 7.0.0
Restrict network access to cFS instances to authorized systems only
Implement additional input validation for CCSDS header processing where possible
Review and enhance network segmentation between ground systems and flight software environments

Patch Information

At the time of publication, the NASA cFS project had been informed of this vulnerability through GitHub Issue #953 but has not yet released an official patch or response. Organizations should monitor the NASA cFS GitHub repository for security updates and patch releases.

Additional vulnerability details are available through VulDB Entry #355079.

Workarounds

Implement network-level filtering to block malformed CCSDS packets before they reach cFS instances
Add custom input validation wrappers around CFE_SB_TransmitMsg function calls to validate header sizes
Deploy the cFS in isolated network segments with strict access controls
Consider implementing application-level sandboxing or memory protection mechanisms where platform capabilities allow

bash

# Network isolation configuration example for cFS environments
# Restrict Software Bus communication to authorized endpoints only
iptables -A INPUT -p udp --dport 1234 -s trusted_ground_station_ip -j ACCEPT
iptables -A INPUT -p udp --dport 1234 -j DROP