CVE-2026-21899 is a medium-severity vulnerability found in NASA's CryptoLib, which 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, this vulnerability allows for an out-of-bounds read due to improper checks in the base64urlDecode function. Specifically, when the input length is zero, the function attempts to dereference input[inputLen - 1], leading to a potential crash.
This vulnerability is classified with a CVSS score of 4.7, indicating a medium severity level. The risk to organizations includes potential process crashes, which could affect the integrity and availability of the system. The vulnerability was disclosed on January 10, 2026, and it has been addressed in version 1.4.3.
Given the nature of this vulnerability, organizations should prioritize patching immediately to mitigate the risk associated with this flaw. Failure to do so may expose systems to crashes during operation.
As of now, there are no known exploits, and the CVE is not listed in the Known Exploited Vulnerabilities (KEV) catalog, indicating that it is not actively exploited in the wild.
Vulnerability Details
The official description of CVE-2026-21899 states: '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, in base64urlDecode, padding-stripping dereferences input[inputLen - 1] before checking that inputLen > 0 or that input != NULL. For inputLen == 0, this becomes an OOB read at input[-1], potentially crashing the process. If input == NULL and inputLen == 0, it dereferences NULL - 1. This issue has been patched in version 1.4.3.'
This vulnerability falls under the CWE-125 category, indicating an out-of-bounds read. The CVSS score of 4.7 highlights a medium impact on confidentiality, integrity, and availability, particularly due to the potential for system crashes.
Technical Analysis
The root cause of this vulnerability lies in the improper handling of input length checks. Specifically, the function fails to ensure that the input length is greater than zero before attempting to access the last byte of the input array. This oversight can lead to an out-of-bounds read, which can crash the process and affect the availability of the system.
The attack vector for this vulnerability is classified as network-based, meaning that an attacker could exploit it remotely. The attack complexity is low, requiring high privileges to exploit the vulnerability effectively. User interaction is not necessary, which increases the risk of exploitation.
The impacts of this vulnerability are characterized as low for confidentiality and integrity, but it has a high impact on availability due to the potential for crashes. Organizations utilizing affected versions of CryptoLib should be aware of the risks associated with this flaw.
Risk & Impact Analysis
Organizations utilizing NASA's CryptoLib need to understand the potential risks this vulnerability poses. The out-of-bounds read could lead to process crashes, affecting operational continuity. Given the low complexity of the exploit and the requirement for high privileges, the potential blast radius may be limited to authorized users, but the impact on availability can be significant.
The vulnerability has a CVSS score of 4.7, suggesting a medium urgency for remediation. While not currently listed in the KEV catalog, organizations should not underestimate the risks associated with this vulnerability and should prepare for potential exploitation.
Organizations should address this vulnerability in their priority patch cycle to mitigate potential risks. The urgency of remediation is medium, and organizations should schedule patching as soon as possible.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
CryptoLib versions prior to 1.4.3 are affected by this vulnerability. Organizations should ensure that they are running the latest version to mitigate the risk associated with this flaw.
Mitigation & Remediation
To mitigate this vulnerability, organizations should upgrade to CryptoLib version 1.4.3 or later, where the issue has been patched. If immediate upgrading is not feasible, organizations should implement workarounds such as input validation to ensure that no null or zero-length inputs are processed.
Additionally, organizations should consider applying configuration hardening to reduce exposure to potential exploits and implement monitoring to detect anomalous behavior indicative of exploitation attempts.
Continuous security testing can also be employed to validate the effectiveness of the applied patches and configurations.
Detection Guidance
Monitoring for this vulnerability should include log indicators associated with the CryptoLib library as well as behavioral anomalies that could suggest exploitation attempts. It is essential to review system changes that may correlate with the vulnerability's exploitation, particularly around the time of known or suspected attacks.
AppSecure Threat Intelligence Insight
CVE-2026-21899 represents a significant issue for organizations using the CryptoLib library, particularly those in the aerospace sector where communication integrity is critical. The vulnerability highlights the importance of rigorous input validation and robust error handling in software development.
As organizations move towards more integrated and automated systems, vulnerabilities like this can have far-reaching impacts. Security teams should adopt a proactive approach to vulnerability management and ensure they are prepared for potential threats.
A vulnerability management program can help organizations identify and mitigate risks effectively, ensuring that vulnerabilities are addressed in a timely manner.
Penetration testing should also be part of the security strategy to identify and eliminate potential weaknesses before they can be exploited.
Cloud penetration testing can further enhance security for organizations utilizing cloud-based systems.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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