CVE-2026-21900 json
CryptoLib Has Out-of-Bounds Read in KMC Encrypt Metadata Parsing via Flawed strtok Pattern
published 2026-01-10 9 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-1894
- cvss
- 5.9
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.6%
- EPSS 0.6% chance of exploitation in 30 days, percentile 48%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- nasa cryptolib 1.4.3
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 9 mo ago
Exploit prediction
0.60% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/nasa/CryptoLib/security/advisories/GHSA-4g6v-36fv-qcvw referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.2 | 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 |
| CNA | 4.0 | 8.2 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| NVD | 3.1 | 5.9 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected products
- nasa CryptoLib
Classification
- Weakness
-
- CWE-125 Out-of-bounds Read
References
-
github.com
/nasa/CryptoLib/commit/2372efd3da1ccb226b4297222e25f41ecc84821d
patch
-
github.com
/nasa/CryptoLib/security/advisories/GHSA-4g6v-36fv-qcvw
exploit, vendor-advisory
-
github.com
/nasa/CryptoLib/releases/tag/v1.4.3
release-notes
Sources
- CVE List CVE-2026-21900
- NVD CVE-2026-21900
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.