CVE-2026-21898 in CryptoLib
Summary
by MITRE • 01/10/2026
CryptoLib provides a software-only solution using the CCSDS Space Data Link Security Protocol - Extended Procedures (SDLS-EP) to secure communications between a spacecraft running the core Flight System (cFS) and a ground station. Prior to version 1.4.3, the Crypto_AOS_ProcessSecurity function reads memory without valid bounds checking when parsing AOS frame hashes. This issue has been patched in version 1.4.3.
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Analysis
by VulDB Data Team • 01/11/2026
The vulnerability described in CVE-2026-21898 resides within the CryptoLib implementation of the CCSDS Space Data Link Security Protocol - Extended Procedures standard, which is specifically designed for securing communications between spacecraft operating on the core Flight System and ground stations. This cryptographic library serves as a critical component in space mission communications where data integrity and security are paramount for mission success and operational safety. The affected system operates within the constrained environment of spaceflight applications where traditional software vulnerabilities can have catastrophic consequences due to the remote and unrecoverable nature of spacecraft operations.
The technical flaw manifests in the Crypto_AOS_ProcessSecurity function where memory access occurs without proper bounds validation during the parsing of AOS frame hashes. This represents a classic buffer over-read vulnerability that falls under CWE-129, specifically related to insufficient bounds checking of array data. The function processes authentication information contained within AOS frames without verifying that the parsed hash data remains within allocated memory boundaries, creating an exploitable condition where an attacker could potentially manipulate the input data to cause unauthorized memory access patterns. This vulnerability is particularly concerning in space applications where the integrity of communication protocols directly impacts mission-critical operations and spacecraft control systems.
The operational impact of this vulnerability extends beyond typical software security concerns due to the specialized nature of space communications and the core Flight System architecture. When an attacker successfully exploits this memory access issue, they could potentially cause the cryptographic processing function to access invalid memory locations, leading to system crashes, data corruption, or potentially more sophisticated attacks that might compromise the security of the entire spacecraft communication chain. The vulnerability affects the integrity verification process of spacecraft communications, which could allow unauthorized parties to inject malicious data into the communication stream or disrupt critical mission operations. According to ATT&CK framework, this vulnerability could be leveraged for privilege escalation or defense evasion techniques within the constrained space environment, where traditional cybersecurity measures may not be fully applicable.
The remediation for this vulnerability was implemented in version 1.4.3 of the CryptoLib software, which introduced proper bounds checking mechanisms to ensure that all memory access operations within the Crypto_AOS_ProcessSecurity function validate input data against predefined limits before processing. This update addresses the root cause by implementing defensive programming practices that prevent unauthorized memory access patterns. Organizations operating spacecraft or ground systems utilizing this cryptographic library must ensure immediate deployment of version 1.4.3 or equivalent patches to maintain the integrity of their space communication systems. The fix demonstrates the importance of robust input validation in security-critical applications, particularly in environments where software failures can result in mission loss or safety hazards. Continuous monitoring and validation of cryptographic implementations remain essential for maintaining secure space communication protocols that protect against both intentional attacks and accidental system failures.