CVE-2026-56016

Full vulnerability record from the local CVENow database.

Description

CGI::Session::ID::md5 versions before 4.49 for Perl generate predictable session ids from low-entropy sources. The generate_id method builds the session id from a MD5 digest of the process id, the epoch time, and the built-in rand() function. All three are predictable, low-entropy sources: the PID is drawn from a small range, the epoch time can be guessed or read from the HTTP Date header, and Perl's rand() is unsuitable for security purposes because it is predictable and reversible. An attacker who predicts a session id can impersonate the corresponding session and bypass authentication.

Severity

MEDIUM

CVSS score

5.9 (v3.1)

Vulnerability status

Deferred

Source identifier

9b29abf9-4ab0-4765-b253-1875cd9b441e

Published

2026-07-01 08:16:21.883000

Last modified

2026-10-25 17:10:00.197000

View original CVE JSON

{
  "id": "CVE-2026-56016",
  "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
  "published": "2026-07-01T08:16:21.883",
  "lastModified": "2026-10-25T17:10:00.197",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "CGI::Session::ID::md5 versions before 4.49 for Perl generate predictable session ids from low-entropy sources.\n\nThe generate_id method builds the session id from a MD5 digest of the process id, the epoch time, and the built-in rand() function. All three are predictable, low-entropy sources: the PID is drawn from a small range, the epoch time can be guessed or read from the HTTP Date header, and Perl's rand() is unsuitable for security purposes because it is predictable and reversible.\n\nAn attacker who predicts a session id can impersonate the corresponding session and bypass authentication."
    },
    {
      "lang": "es",
      "value": "Las versiones de CGI::Session::ID::md5 anteriores a la 4.49 para Perl generan identificadores de sesión predecibles a partir de fuentes de baja entropía.\n\nEl método generate_id construye el identificador de sesión a partir de un resumen MD5 del ID del proceso, el tiempo de época y la función rand() incorporada. Las tres son fuentes predecibles y de baja entropía: el PID se extrae de un rango pequeño, el tiempo de época puede adivinarse o leerse del encabezado HTTP Date, y la función rand() de Perl no es adecuada para fines de seguridad porque es predecible y reversible.\n\nUn atacante que predice un identificador de sesión puede suplantar la sesión correspondiente y eludir la autenticación."
    }
  ],
  "affected": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "affectedData": [
        {
          "vendor": "MARKSTOS",
          "product": "CGI::Session::ID::md5",
          "defaultStatus": "unaffected",
          "collectionURL": "https://cpan.org/modules",
          "packageName": "CGI-Session",
          "programFiles": [
            "lib/CGI/Session/ID/md5.pm"
          ],
          "programRoutines": [
            {
              "name": "CGI::Session::ID::md5::generate_id"
            }
          ],
          "repo": "http://github.com/cromedome/cgi-session",
          "versions": [
            {
              "version": "0",
              "lessThan": "4.49",
              "versionType": "custom",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
          "baseScore": 5.9,
          "baseSeverity": "MEDIUM",
          "attackVector": "NETWORK",
          "attackComplexity": "HIGH",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 3.6
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-07-01T14:03:10.013809Z",
          "id": "CVE-2026-56016",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-338"
        },
        {
          "lang": "en",
          "value": "CWE-340"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/changes",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/source/lib/CGI/Session/ID/md5.pm",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "http://www.openwall.com/lists/oss-security/2026/07/01/6",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ]
}