CVE-2026-21899 MEDIUM

CVE-2026-21899: CryptoLib has an out-of-bounds read and crash vulnerability when decoding an empty Base64url string

Vendor Nasa
Product CryptoLib
Weakness CWE-125
Published January 10, 2026
Last update January 12, 2026

CVSS base score

4.7/10
Attack vector Network
Attack complexity Low
Privileges required High
User interaction None
Confidentiality Low
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

January 10, 2026 CVE published
January 12, 2026 Record updated