Medium severity · published Jan 10, 2026
CVE-2026-21899
CryptoLib has an out-of-bounds read and crash vulnerability when decoding an empty Base64url string
4.9
CVSS
0.3%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 28% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CR
CryptoLib · nasa
< 1.4.3 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-21899
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-21899
Release Notes
https://github.com/nasa/CryptoLib/releases/tag/v1.4.3
Exploit
https://github.com/nasa/CryptoLib/security/advisories/GHSA-wc29-5hw7-mpj8
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