CVE-2026-21899: nasa cryptolib Out-of-bounds Read

Vulnerability summary

CVE-2026-21899 is a medium (CVSS 4.9) Out-of-bounds Read vulnerability in nasa cryptolib. EPSS estimates a 0.34% chance of exploitation in the next 30 days, higher than 26.5% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 10-01-2026
   PublishedVulnerability first disclosed.
2. 12-01-2026
   Last modifiedVulnerability information updated.

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.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.