Vulnerability · Published Jan 10, 2026 · Assigned by GitHub_M

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

High 8.2

In plain English

A high-severity out-of-bounds read in CryptoLib from nasa. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities).

Severity (CVSS 4.0)8.2High

Exploit odds (30 days)0.6%top 51.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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 (as reported)

Vendor	Product	Versions
nasa	CryptoLib	< 1.4.3

Weakness: CWE-125 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References

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