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

{
  "id": "eb97d6110e4adc4f8b863cd48adfb9a028384fb06daaf87ce2ba4342f15b75d2",
  "url": "https://osv.dev/vulnerability/CVE-2026-21900",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CryptoLib Has Out-of-Bounds Read in KMC Encrypt Metadata Parsing via Flawed strtok Pattern",
    "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.",
    "evidence": "osv:CVE-2026-21900",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-21900",
      "aliases": [
        "CVE-2026-21900",
        "GHSA-4g6v-36fv-qcvw"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/nasa/cryptolib",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "9ffda0ff78e8f74c58db4c181923196870e04c3e"
                },
                {
                  "fixed": "2372efd3da1ccb226b4297222e25f41ecc84821d"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:nasa:cryptolib:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.4.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "2372efd3da1ccb226b4297222e25f41ecc84821d"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "9ffda0ff78e8f74c58db4c181923196870e04c3e"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v1.4.3"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.4.2",
            "v1.4.0",
            "v1.3.3",
            "v1.3.2",
            "v1.3.1",
            "v1.3.0",
            "v1.2.3",
            "v1.2.2",
            "v1.2.1",
            "v1.2.0",
            "v1.1.1",
            "v1.1.0",
            "v1.0.3"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-21900.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:37.839917169Z",
      "provider": "osv",
      "references": [
        "https://github.com/nasa/CryptoLib/releases/tag/v1.4.3",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21900.json",
        "https://github.com/nasa/CryptoLib/security/advisories/GHSA-4g6v-36fv-qcvw",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-21900",
        "https://github.com/nasa/CryptoLib/commit/2372efd3da1ccb226b4297222e25f41ecc84821d"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-125"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/21xxx/CVE-2026-21900.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-21900",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 505089,
  "published_at": "2026-01-10T00:14:33.782+00:00"
}