What’s Vulnerable › Vulnerabilities

CVE-2026-21900: CryptoLib Has Out-of-Bounds Read in KMC Encrypt Metadata Parsing via Flawed strtok Pattern

• Severity: medium (CVSS 5.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% 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, 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.

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/commit/2372efd3da1ccb226b4297222e25f41ecc84821d
• https://github.com/nasa/CryptoLib/releases/tag/v1.4.3
• https://github.com/nasa/CryptoLib/security/advisories/GHSA-4g6v-36fv-qcvw
• https://github.com/nasa/CryptoLib/security/advisories/GHSA-4g6v-36fv-qcvw

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