Out-of-bounds Read in Nasa Cryptolib
CVE-2026-21900
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (45.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 45.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001
Affected products
- Nasa Cryptolib — versions < 1.4.3
Weakness classification (CWE)
References
- github.com/nasa/CryptoLib/security/advisories/GHSA-4g6v-36fv-qcvw (Exploit, Vendor Advisory)
- github.com/nasa/CryptoLib/commit/2372efd3da1ccb226b4297222e25f41ecc84821d (Patch)
- github.com/nasa/CryptoLib/releases/tag/v1.4.3 (Release Notes)
Frequently asked questions
- What is CVE-2026-21900?
- CVE-2026-21900 is a medium-severity vulnerability in Nasa Cryptolib, classified under Out-of-bounds Read. CVSS score: 5.9/10. Published 2026-01-10.
- How severe is CVE-2026-21900?
- Medium severity. CVSS v3 base score is 5.9 out of 10.