Out-of-bounds Read in Nasa Cryptolib
CVE-2026-21899
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.004 (26.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 26th percentile — 26.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.000
Affected products
- Nasa Cryptolib — versions < 1.4.3
Weakness classification (CWE)
References
- github.com/nasa/CryptoLib/security/advisories/GHSA-wc29-5hw7-mpj8 (Exploit, Vendor Advisory)
- github.com/nasa/CryptoLib/releases/tag/v1.4.3 (Release Notes)
Frequently asked questions
- What is CVE-2026-21899?
- CVE-2026-21899 is a medium-severity vulnerability in Nasa Cryptolib, classified under Out-of-bounds Read. CVSS score: 4.7/10. Published 2026-01-10.
- How severe is CVE-2026-21899?
- Medium severity. CVSS v3 base score is 4.7 out of 10.