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CVE-2026-4115

Estado: ModificadaBaja (2.9)—

A vulnerability was detected in PuTTY 0.83. Affected is the function eddsa_verify of the file crypto/ecc-ssh.c of the component Ed25519 Signature Handler. The manipulation results in improper verification of cryptographic signature. The attack may be performed from remote. The attack requires a high level of complexity. The exploitability is told to be difficult. The exploit is now public and may be used. The real existence of this vulnerability is still doubted at the moment. The patch is identified as af996b5ec27ab79bae3882071b9d6acf16044549.

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It is advisable to implement a patch to correct this issue. The vendor was contacted early, responded in a very professional manner and quickly released a patch for the affected product. However, at the moment there is no proof that this flaw might have any real-world impact.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Putty — Putty

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-4115",
  "cveTags": [
    {
      "tags": [
        "disputed"
      ],
      "sourceIdentifier": "cna@vuldb.com"
    }
  ],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-4115",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-03-23T15:32:32.298237Z"
        }
      }
    ],
    "cvssMetricV2": [
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        "type": "Secondary",
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          "baseScore": 2.6,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:H/Au:N/C:N/I:P/A:N",
          "authentication": "NONE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "HIGH",
          "availabilityImpact": "NONE",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "LOW",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 4.9,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
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    "cvssMetricV31": [
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        "type": "Secondary",
        "source": "cna@vuldb.com",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 3.7,
          "attackVector": "NETWORK",
          "baseSeverity": "LOW",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "NONE",
          "attackComplexity": "HIGH",
          "availabilityImpact": "NONE",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
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        "exploitabilityScore": 2.2
      }
    ],
    "cvssMetricV40": [
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        "type": "Secondary",
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        "cvssData": {
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          "version": "4.0",
          "Recovery": "NOT_DEFINED",
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          "Automatable": "NOT_DEFINED",
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          "baseSeverity": "LOW",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/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",
          "exploitMaturity": "PROOF_OF_CONCEPT",
          "providerUrgency": "NOT_DEFINED",
          "userInteraction": "NONE",
          "attackComplexity": "HIGH",
          "attackRequirements": "NONE",
          "privilegesRequired": "NONE",
          "subIntegrityImpact": "NONE",
          "vulnIntegrityImpact": "LOW",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "vulnAvailabilityImpact": "NONE",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
        }
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    ]
  },
  "affected": [
    {
      "source": "cna@vuldb.com",
      "affectedData": [
        {
          "cpes": [
            "cpe:2.3:a:putty:putty:*:*:*:*:*:*:*:*"
          ],
          "vendor": "n/a",
          "modules": [
            "Ed25519 Signature Handler"
          ],
          "product": "PuTTY",
          "versions": [
            {
              "status": "affected",
              "version": "0.83"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-03-22T13:16:20.377",
  "references": [
    {
      "url": "https://git.tartarus.org/?p=simon/putty.git;a=commitdiff;h=af996b5ec27ab79bae3882071b9d6acf16044549",
      "tags": [
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      "source": "cna@vuldb.com"
    },
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      "url": "https://github.com/py-thok/putty-ed25519-malleability-s-plus-l",
      "tags": [
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    },
    {
      "url": "https://github.com/py-thok/putty-ed25519-malleability-s-plus-l/blob/main/poc.py",
      "tags": [
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      "tags": [
        "Permissions Required",
        "VDB Entry"
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    },
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      "url": "https://vuldb.com/?id.352429",
      "tags": [
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        "VDB Entry"
      ],
      "source": "cna@vuldb.com"
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      "url": "https://vuldb.com/?submit.775576",
      "tags": [
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        "VDB Entry"
      ],
      "source": "cna@vuldb.com"
    },
    {
      "url": "https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/eddsa-overlarge-s.html",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "cna@vuldb.com"
    },
    {
      "url": "https://www.rfc-editor.org/rfc/rfc8032#section-8.4",
      "tags": [
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      ],
      "source": "cna@vuldb.com"
    },
    {
      "url": "http://www.openwall.com/lists/oss-security/2026/05/24/11",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "cna@vuldb.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-345"
        },
        {
          "lang": "en",
          "value": "CWE-347"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "A vulnerability was detected in PuTTY 0.83. Affected is the function eddsa_verify of the file crypto/ecc-ssh.c of the component Ed25519 Signature Handler. The manipulation results in improper verification of cryptographic signature. The attack may be performed from remote. The attack requires a high level of complexity. The exploitability is told to be difficult. The exploit is now public and may be used. The real existence of this vulnerability is still doubted at the moment. The patch is identified as af996b5ec27ab79bae3882071b9d6acf16044549. It is advisable to implement a patch to correct this issue. The vendor was contacted early, responded in a very professional manner and quickly released a patch for the affected product. However, at the moment there is no proof that this flaw might have any real-world impact."
    },
    {
      "lang": "es",
      "value": "Una vulnerabilidad fue detectada en PuTTY 0.83. Afectada es la función eddsa_verify del archivo crypto/ecc-ssh.c del componente Gestor de Firma Ed25519. La manipulación resulta en verificación impropia de firma criptográfica. El ataque puede ser realizado desde remoto. El ataque requiere un alto nivel de complejidad. La explotabilidad se dice que es difícil. El exploit es ahora público y puede ser usado. La existencia real de esta vulnerabilidad todavía se duda en este momento. El parche se identifica como af996b5ec27ab79bae3882071b9d6acf16044549. Es aconsejable implementar un parche para corregir este problema. El proveedor fue contactado temprano, respondió de manera muy profesional y rápidamente lanzó un parche para el producto afectado. Sin embargo, en este momento no hay prueba de que este fallo pueda tener algún impacto en el mundo real."
    }
  ],
  "lastModified": "2026-06-17T10:56:00.850",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:putty:putty:0.83:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "996A8841-3079-4C8D-A996-C1A75B2D788E"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cna@vuldb.com"
}