FKIE_CVE-2026-3706

Vulnerability from fkie_nvd - Published: 2026-03-08 05:16 - Updated: 2026-04-22 21:27
Severity ?
3.7 (Low) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Summary
A vulnerability was determined in mkj Dropbear up to 2025.89. Impacted is the function unpackneg of the file src/curve25519.c of the component S Range Check. This manipulation causes improper verification of cryptographic signature. The attack can be initiated remotely. The attack is considered to have high complexity. The exploitability is considered difficult. The actual existence of this vulnerability is currently in question. Patch name: fdec3c90a15447bd538641d85e5a3e3ac981011d. To fix this issue, it is recommended to deploy a patch. The project maintainer explains: "Signature Malleability is not exploitable in SSH protocol. (...) [A] PoC doesn't exist for SSH implementation, but rather it's against the internal API."
References
cna@vuldb.comhttps://github.com/mkj/dropbear/
cna@vuldb.comhttps://github.com/mkj/dropbear/commit/fdec3c90a15447bd538641d85e5a3e3ac981011d
cna@vuldb.comhttps://github.com/mkj/dropbear/issues/406
cna@vuldb.comhttps://github.com/mkj/dropbear/pull/407
cna@vuldb.comhttps://github.com/str4d/ed25519-java/issues/82#issue-727629226
cna@vuldb.comhttps://vuldb.com/?ctiid.349652
cna@vuldb.comhttps://vuldb.com/?id.349652
cna@vuldb.comhttps://vuldb.com/?submit.765933
134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/mkj/dropbear/issues/406
Impacted products
Vendor Product Version
To clipboard 

{
  "cveTags": [
    {
      "sourceIdentifier": "cna@vuldb.com",
      "tags": [
        "disputed"
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "A vulnerability was determined in mkj Dropbear up to 2025.89. Impacted is the function unpackneg of the file src/curve25519.c of the component S Range Check. This manipulation causes improper verification of cryptographic signature. The attack can be initiated remotely. The attack is considered to have high complexity. The exploitability is considered difficult. The actual existence of this vulnerability is currently in question. Patch name: fdec3c90a15447bd538641d85e5a3e3ac981011d. To fix this issue, it is recommended to deploy a patch. The project maintainer explains: \"Signature Malleability is not exploitable in SSH protocol. (...) [A] PoC doesn\u0027t exist for SSH implementation, but rather it\u0027s against the internal API.\""
    },
    {
      "lang": "es",
      "value": "Se determin\u00f3 una vulnerabilidad en mkj Dropbear hasta 2025.89. La funci\u00f3n unpackneg del archivo src/curve25519.c del componente S Range Check se ve afectada. Esta manipulaci\u00f3n provoca una verificaci\u00f3n incorrecta de la firma criptogr\u00e1fica. El ataque puede iniciarse de forma remota. Se considera que el ataque tiene una complejidad alta. La explotabilidad se considera dif\u00edcil. El exploit ha sido divulgado p\u00fablicamente y puede ser utilizado. Nombre del parche: fdec3c90a15447bd538641d85e5a3e3ac981011d. Para solucionar este problema, se recomienda desplegar un parche."
    }
  ],
  "id": "CVE-2026-3706",
  "lastModified": "2026-04-22T21:27:27.950",
  "metrics": {
    "cvssMetricV2": [
      {
        "acInsufInfo": false,
        "baseSeverity": "LOW",
        "cvssData": {
          "accessComplexity": "HIGH",
          "accessVector": "NETWORK",
          "authentication": "NONE",
          "availabilityImpact": "NONE",
          "baseScore": 2.6,
          "confidentialityImpact": "NONE",
          "integrityImpact": "PARTIAL",
          "vectorString": "AV:N/AC:H/Au:N/C:N/I:P/A:N",
          "version": "2.0"
        },
        "exploitabilityScore": 4.9,
        "impactScore": 2.9,
        "obtainAllPrivilege": false,
        "obtainOtherPrivilege": false,
        "obtainUserPrivilege": false,
        "source": "cna@vuldb.com",
        "type": "Secondary",
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 3.7,
          "baseSeverity": "LOW",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 1.4,
        "source": "cna@vuldb.com",
        "type": "Secondary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "HIGH",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 1.7,
          "baseSeverity": "LOW",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "UNREPORTED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "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:U/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",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "cna@vuldb.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-03-08T05:16:31.847",
  "references": [
    {
      "source": "cna@vuldb.com",
      "url": "https://github.com/mkj/dropbear/"
    },
    {
      "source": "cna@vuldb.com",
      "url": "https://github.com/mkj/dropbear/commit/fdec3c90a15447bd538641d85e5a3e3ac981011d"
    },
    {
      "source": "cna@vuldb.com",
      "url": "https://github.com/mkj/dropbear/issues/406"
    },
    {
      "source": "cna@vuldb.com",
      "url": "https://github.com/mkj/dropbear/pull/407"
    },
    {
      "source": "cna@vuldb.com",
      "url": "https://github.com/str4d/ed25519-java/issues/82#issue-727629226"
    },
    {
      "source": "cna@vuldb.com",
      "url": "https://vuldb.com/?ctiid.349652"
    },
    {
      "source": "cna@vuldb.com",
      "url": "https://vuldb.com/?id.349652"
    },
    {
      "source": "cna@vuldb.com",
      "url": "https://vuldb.com/?submit.765933"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/mkj/dropbear/issues/406"
    }
  ],
  "sourceIdentifier": "cna@vuldb.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-345"
        },
        {
          "lang": "en",
          "value": "CWE-347"
        }
      ],
      "source": "cna@vuldb.com",
      "type": "Secondary"
    }
  ]
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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