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CVE-2026-48859

Full vulnerability record from the local CVENow database.

Description

Observable Timing Discrepancy vulnerability in Erlang/OTP ssh (ssh_auth, ssh_options modules) allows unauthenticated remote username enumeration via timing side-channel in password authentication. When the SSH daemon is configured with the user_passwords or password option, ssh_auth:check_password/3 performs a PBKDF2-SHA256 computation with 600,000 iterations (~300ms) for valid usernames, but returns immediately (~0ms) for invalid usernames via the ssh_options:get_password_option/2 path. This timing difference is detectable in a single authentication attempt and allows an unauthenticated attacker to distinguish valid from invalid usernames. The user_passwords and password options are documented as intended for test purposes; the recommended alternative is pwdfun, which is not affected by this vulnerability. This vulnerability is associated with program files lib/ssh/src/ssh_auth.erl and lib/ssh/src/ssh_options.erl. This issue affects OTP from OTP 29.0 before OTP 29.0.2, corresponding to ssh from 6.0 before 6.0.1.

Severity
MEDIUM
CVSS score
6.3 (v4.0)
Vulnerability status
Modified
Source identifier
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Published
2026-06-10 16:17:12.373000
Last modified
2026-10-26 11:10:00.157000
View original CVE JSON 
{
  "id": "CVE-2026-48859",
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "published": "2026-06-10T16:17:12.373",
  "lastModified": "2026-10-26T11:10:00.157",
  "vulnStatus": "Modified",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Observable Timing Discrepancy vulnerability in Erlang/OTP ssh (ssh_auth, ssh_options modules) allows unauthenticated remote username enumeration via timing side-channel in password authentication.\n\nWhen the SSH daemon is configured with the user_passwords or password option, ssh_auth:check_password/3 performs a PBKDF2-SHA256 computation with 600,000 iterations (~300ms) for valid usernames, but returns immediately (~0ms) for invalid usernames via the ssh_options:get_password_option/2 path. This timing difference is detectable in a single authentication attempt and allows an unauthenticated attacker to distinguish valid from invalid usernames.\n\nThe user_passwords and password options are documented as intended for test purposes; the recommended alternative is pwdfun, which is not affected by this vulnerability.\n\nThis vulnerability is associated with program files lib/ssh/src/ssh_auth.erl and lib/ssh/src/ssh_options.erl.\n\nThis issue affects OTP from OTP 29.0 before OTP 29.0.2, corresponding to ssh from 6.0 before 6.0.1."
    },
    {
      "lang": "es",
      "value": "Vulnerabilidad de discrepancia de tiempo observable en Erlang/OTP ssh (módulos ssh_auth, ssh_options) permite la enumeración remota de nombres de usuario no autenticados a través de un canal lateral de tiempo en la autenticación de contraseña.\n\nCuando el demonio SSH está configurado con la opción user_passwords o password, ssh_auth:check_password/3 realiza un cálculo PBKDF2-SHA256 con 600.000 iteraciones (~300ms) para nombres de usuario válidos, pero regresa inmediatamente (~0ms) para nombres de usuario inválidos a través de la ruta ssh_options:get_password_option/2. Esta diferencia de tiempo es detectable en un solo intento de autenticación y permite a un atacante no autenticado distinguir nombres de usuario válidos de inválidos.\n\nLas opciones user_passwords y password están documentadas como destinadas a fines de prueba; la alternativa recomendada es pwdfun, que no se ve afectada por esta vulnerabilidad.\n\nEsta vulnerabilidad está asociada con los archivos de programa lib/ssh/src/ssh_auth.erl y lib/ssh/src/ssh_options.erl.\n\nEste problema afecta a OTP desde OTP 29.0 antes de 29.0.2 correspondiente a ssh desde 6.0 antes de 6.0.1."
    }
  ],
  "affected": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "affectedData": [
        {
          "vendor": "Erlang",
          "product": "OTP",
          "defaultStatus": "unaffected",
          "packageName": "otp",
          "cpes": [
            "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"
          ],
          "modules": [
            "ssh_auth",
            "ssh_options"
          ],
          "programFiles": [
            "lib/ssh/src/ssh_auth.erl",
            "lib/ssh/src/ssh_options.erl"
          ],
          "programRoutines": [
            {
              "name": "ssh_auth:check_password/3"
            },
            {
              "name": "ssh_options:get_password_option/2"
            }
          ],
          "packageURL": "pkg:software-id/erlang.org/otp",
          "versions": [
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              "version": "29.0",
              "lessThan": "29.0.2",
              "versionType": "otp",
              "status": "affected"
            }
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        },
        {
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          "product": "OTP",
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          "packageName": "ssh",
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          "modules": [
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          ],
          "programFiles": [
            "src/ssh_auth.erl",
            "src/ssh_options.erl"
          ],
          "programRoutines": [
            {
              "name": "ssh_auth:check_password/3"
            },
            {
              "name": "ssh_options:get_password_option/2"
            }
          ],
          "repo": "https://github.com/erlang/otp",
          "packageURL": "pkg:otp/ssh?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git",
          "versions": [
            {
              "version": "6.0",
              "lessThan": "6.0.1",
              "versionType": "otp",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Erlang",
          "product": "OTP",
          "defaultStatus": "unaffected",
          "collectionURL": "https://github.com",
          "packageName": "erlang/otp",
          "cpes": [
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          ],
          "modules": [
            "ssh_auth",
            "ssh_options"
          ],
          "programFiles": [
            "lib/ssh/src/ssh_auth.erl",
            "lib/ssh/src/ssh_options.erl"
          ],
          "programRoutines": [
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              "name": "ssh_auth:check_password/3"
            },
            {
              "name": "ssh_options:get_password_option/2"
            }
          ],
          "repo": "https://github.com/erlang/otp",
          "packageURL": "pkg:github/erlang/otp",
          "versions": [
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              "version": "032d1bc9491a3975c68faf9bc7776115d6ae3005",
              "lessThan": "c342092ef4b369bb409d5b71ac8fd83bab74aedf",
              "versionType": "git",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
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        "type": "Secondary",
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          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/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",
          "baseScore": 6.3,
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          "vulnIntegrityImpact": "NONE",
          "vulnAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "subAvailabilityImpact": "NONE",
          "exploitMaturity": "NOT_DEFINED",
          "confidentialityRequirement": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "valueDensity": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED"
        }
      }
    ],
    "cvssMetricV31": [
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        "source": "[email protected]",
        "type": "Primary",
        "cvssData": {
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          "integrityImpact": "NONE",
          "availabilityImpact": "NONE"
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    "ssvcV203": [
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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          "options": [
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              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
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  "weaknesses": [
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      "description": [
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          "lang": "en",
          "value": "CWE-208"
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  "configurations": [
    {
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          "operator": "OR",
          "negate": false,
          "cpeMatch": [
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              "criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
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  "references": [
    {
      "url": "https://cna.erlef.org/cves/CVE-2026-48859.html",
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "tags": [
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}