CVE-2026-56016

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.

CVSS v3 5.9 MEDIUM

5.9^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.2 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/changes
https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/source/lib/CGI/Session/ID/md5.pm
http://www.openwall.com/lists/oss-security/2026/07/01/6

Configurations

No configuration.

History

25 Oct 2026, 17:10

Type	Values Removed	Values Added
Summary		(es) 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. El 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. Un atacante que predice un identificador de sesión puede suplantar la sesión correspondiente y eludir la autenticación.

Information

Published : 2026-07-01 08:16

Updated : 2026-10-25 17:10

NVD link : CVE-2026-56016

Mitre link : CVE-2026-56016

CVE.ORG link : CVE-2026-56016

JSON object : View

Products Affected

No product.

CWE

CWE-338

Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

CWE-340

Generation of Predictable Numbers or Identifiers

{"id": "CVE-2026-56016", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-56016", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-07-01T14:03:10.013809Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.9, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 3.6, "exploitabilityScore": 2.2}]}, "affected": [{"source": "9b29abf9-4ab0-4765-b253-1875cd9b441e", "affectedData": [{"repo": "http://github.com/cromedome/cgi-session", "vendor": "MARKSTOS", "product": "CGI::Session::ID::md5", "versions": [{"status": "affected", "version": "0", "lessThan": "4.49", "versionType": "custom"}], "packageName": "CGI-Session", "programFiles": ["lib/CGI/Session/ID/md5.pm"], "collectionURL": "https://cpan.org/modules", "defaultStatus": "unaffected", "programRoutines": [{"name": "CGI::Session::ID::md5::generate_id"}]}]}], "published": "2026-07-01T08:16:21.883", "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"}], "vulnStatus": "Deferred", "weaknesses": [{"type": "Secondary", "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e", "description": [{"lang": "en", "value": "CWE-338"}, {"lang": "en", "value": "CWE-340"}]}], "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 sesi\u00f3n predecibles a partir de fuentes de baja entrop\u00eda.\n\nEl m\u00e9todo generate_id construye el identificador de sesi\u00f3n a partir de un resumen MD5 del ID del proceso, el tiempo de \u00e9poca y la funci\u00f3n rand() incorporada. Las tres son fuentes predecibles y de baja entrop\u00eda: el PID se extrae de un rango peque\u00f1o, el tiempo de \u00e9poca puede adivinarse o leerse del encabezado HTTP Date, y la funci\u00f3n rand() de Perl no es adecuada para fines de seguridad porque es predecible y reversible.\n\nUn atacante que predice un identificador de sesi\u00f3n puede suplantar la sesi\u00f3n correspondiente y eludir la autenticaci\u00f3n."}], "lastModified": "2026-10-25T17:10:00.197", "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e"}