CVE-2026-21899: Nasa Cryptolib

Medium severity, CVSS 4.9. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Nasa Cryptolib: before 1.4.3 (fixed in 1.4.3)

Published 2026-01-10. Last modified 2026-06-17.