Security advisory

{
  "id": "482728283a5411cf5189fbfa6400e0b5274d7ed74f0c03d4dfdcc99bd92b2aea",
  "url": "https://osv.dev/vulnerability/CVE-2021-40818",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-40818",
    "summary": "scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.",
    "evidence": "osv:CVE-2021-40818",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2021-40818",
      "aliases": [
        "CVE-2021-40818"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/babelouest/glewlwyd",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "be4cfc79dc15bd4049e83b16ed42619188fcdc19"
                },
                {
                  "fixed": "0efd112bb62f566877750ad62ee828bff579b4e2"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:glewlwyd_sso_server_project:glewlwyd_sso_server:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "2.5.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "0efd112bb62f566877750ad62ee828bff579b4e2"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.5.3",
            "v2.5.2",
            "v2.5.1",
            "v2.5.0",
            "v2.4.0",
            "v2.3.2",
            "v2.3.1",
            "v2.3.0",
            "v2.2.0",
            "v2.1.1",
            "v2.1.0",
            "v2.0.0",
            "v2.0.0-rc2",
            "v2.0.0-rc1",
            "v2.0.0-b3",
            "v2.0.0-b2",
            "v2.0.0-b1",
            "v1.4.9",
            "v1.4.3",
            "v1.4.8",
            "v1.4.7",
            "v1.4.6",
            "v1.4.4",
            "v1.4.2",
            "v1.4.1",
            "v1.4.0",
            "v1.3.3",
            "v1.3.2",
            "v1.3.1",
            "v1.3",
            "v1.2.4",
            "v1.2.3",
            "1.2.2",
            "1.2.1",
            "1.2",
            "1.1.2",
            "1.1.1",
            "1.1",
            "1.0.1",
            "1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-40818.json",
            "vanir_signatures": [
              {
                "id": "CVE-2021-40818-b9a9e2eb",
                "digest": {
                  "threshold": 0.9,
                  "line_hashes": [
                    "168899953365864851267981944936224712259",
                    "306939930381762482973842239077045014917",
                    "56575773891186167261748599342867103158",
                    "141761113036750274431146595629731944791",
                    "261807869261021487752498520231737758498",
                    "288103742552405928151620312333405988171",
                    "34442594092473031831558547911119189434",
                    "254435195848689549774795497938078147305",
                    "287646012871357051546361415809115228097",
                    "100236071656211006069040019061793134698",
                    "73805413493150671406720583934818328105"
                  ]
                },
                "source": "https://github.com/babelouest/glewlwyd/commit/0efd112bb62f566877750ad62ee828bff579b4e2",
                "target": {
                  "file": "src/scheme/webauthn.c"
                },
                "deprecated": false,
                "signature_type": "Line",
                "signature_version": "v1"
              },
              {
                "id": "CVE-2021-40818-c8d95147",
                "digest": {
                  "length": 5021,
                  "function_hash": "269540315022749937522289855017545701464"
                },
                "source": "https://github.com/babelouest/glewlwyd/commit/0efd112bb62f566877750ad62ee828bff579b4e2",
                "target": {
                  "file": "src/scheme/webauthn.c",
                  "function": "check_attestation_fido_u2f"
                },
                "deprecated": false,
                "signature_type": "Function",
                "signature_version": "v1"
              }
            ],
            "vanir_signatures_modified": "2026-10-20T14:29:24Z"
          }
        }
      ],
      "modified": "2026-10-20T14:29:24.809461851Z",
      "provider": "osv",
      "references": [
        "https://bugs.debian.org/993867",
        "https://github.com/babelouest/glewlwyd/commit/0efd112bb62f566877750ad62ee828bff579b4e2"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-40818",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 389074,
  "published_at": "2021-09-08T22:15:11.383+00:00"
}