What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 4.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-01-10 · updated 2026-06-17
• Weakness: CWE-125

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.

Affected products

• nasa CryptoLib: before 1.4.3 — fixed in 1.4.3

How to fix

Upgrade to a fixed version: nasa CryptoLib 1.4.3. Check the vendor advisory for mitigations.

References

• https://github.com/nasa/CryptoLib/releases/tag/v1.4.3
• https://github.com/nasa/CryptoLib/security/advisories/GHSA-wc29-5hw7-mpj8

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