CVE-2026-21900: nasa cryptolib Out-of-bounds Read

Vulnerability summary

CVE-2026-21900 is a high (CVSS 8.2) Out-of-bounds Read vulnerability in nasa cryptolib. EPSS estimates a 0.60% chance of exploitation in the next 30 days, higher than 47.6% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 10-01-2026
   PublishedVulnerability first disclosed.
2. 13-01-2026
   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, an out-of-bounds heap read vulnerability in cryptography_encrypt() occurs when parsing JSON metadata from KMC server responses. The flawed strtok iteration pattern uses ptr + strlen(ptr) + 1 which reads one byte past allocated buffer boundaries when processing short or malformed metadata strings. 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.