CVE-2026-33936

{
  "id": "CVE-2026-33936",
  "sourceIdentifier": "[email protected]",
  "published": "2026-03-27T23:17:13.733",
  "lastModified": "2026-10-26T22:10:00.163",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "The `ecdsa` PyPI package is a pure Python implementation of ECC (Elliptic Curve Cryptography) with support for ECDSA (Elliptic Curve Digital Signature Algorithm), EdDSA (Edwards-curve Digital Signature Algorithm) and ECDH (Elliptic Curve Diffie-Hellman). Prior to version 0.19.2, an issue in the low-level DER parsing functions can cause unexpected exceptions to be raised from the public API functions. `ecdsa.der.remove_octet_string()` accepts truncated DER where the encoded length exceeds the available buffer. For example, an OCTET STRING that declares a length of 4096 bytes but provides only 3 bytes is parsed successfully instead of being rejected. Because of that, a crafted DER input can cause `SigningKey.from_der()` to raise an internal exception (`IndexError: index out of bounds on dimension 1`) rather than cleanly rejecting malformed DER (e.g., raising `UnexpectedDER` or `ValueError`). Applications that parse untrusted DER private keys may crash if they do not handle unexpected exceptions, resulting in a denial of service. Version 0.19.2 patches the issue."
    },
    {
      "lang": "es",
      "value": "El paquete “ecdsa” de PyPI es una implementación pura en Python de Criptografía de Curva Elíptica (ECC) con soporte para el Algoritmo de Firma Digital de Curva Elíptica (ECDSA), el Algoritmo de Firma Digital de Curva de Edwards (EdDSA) y Diffie-Hellman de Curva Elíptica (ECDH). Antes de la versión 0.19.2, un problema en las funciones de análisis DER de bajo nivel puede causar que se lancen excepciones inesperadas desde las funciones de la API pública. “ecdsa.der.remove_octet_string()” acepta DER truncado donde la longitud codificada excede el búfer disponible. Por ejemplo, una CADENA DE OCTETOS que declara una longitud de 4096 bytes pero proporciona solo 3 bytes se analiza correctamente en lugar de ser rechazada. Debido a esto, una entrada DER manipulada puede causar que “SigningKey.from_der()” lance una excepción interna (“IndexError: índice fuera de los límites en la dimensión 1”) en lugar de rechazar limpiamente el DER malformado (por ejemplo, lanzando “UnexpectedDER” o “ValueError”). Las aplicaciones que analizan claves privadas DER no confiables pueden fallar si no manejan las excepciones inesperadas, lo que resulta en una denegación de servicio. La versión 0.19.2 corrige el problema."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "tlsfuzzer",
          "product": "python-ecdsa",
          "versions": [
            {
              "version": "< 0.19.2",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "LOW"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-04-01T13:44:27.418372Z",
          "id": "CVE-2026-33936",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-20"
        },
        {
          "lang": "en",
          "value": "CWE-130"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:tlsfuzzer:ecdsa:*:*:*:*:*:python:*:*",
              "versionEndExcluding": "0.19.2",
              "matchCriteriaId": "E96A1566-0D57-48AB-A82C-2C5101EB5318"
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  "references": [
    {
      "url": "https://github.com/tlsfuzzer/python-ecdsa/commit/bd66899550d7185939bf27b75713a2ac9325a9d3",
      "source": "[email protected]",
      "tags": [
        "Patch"
      ]
    },
    {
      "url": "https://github.com/tlsfuzzer/python-ecdsa/releases/tag/python-ecdsa-0.19.2",
      "source": "[email protected]",
      "tags": [
        "Product",
        "Release Notes"
      ]
    },
    {
      "url": "https://github.com/tlsfuzzer/python-ecdsa/security/advisories/GHSA-9f5j-8jwj-x28g",
      "source": "[email protected]",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ]
    }
  ]
}