Apache::Session::Generate::ModUniqueId versions from 1.54 through 1.94 for Perl session ids are insecure.
Apache::Session::Generate::ModUniqueId (added in version 1.54) uses the value of the UNIQUE_ID environment variable for the session id. The UNIQUE_ID variable is set by the Apache mod_unique_id plugin, which generates unique ids for the request. The id is based on the IPv4 address, the process id, the epoch time, a 16-bit counter and a thread index, with no obfuscation.
The server IP is often available to the public, and if not available, can be guessed from previous session ids being issued. The process ids may also be guessed from previous session ids. The timestamp is easily guessed (and leaked in the HTTP Date response header).
The purpose of mod_unique_id is to assign a unique id to requests so that events can be correlated in different logs. The id is not designed, nor is it suitable for security purposes.
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{
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"dateUpdated": "2026-07-15T00:46:26.786Z",
"dateReserved": "2026-03-28T19:10:32.393Z",
"datePublished": "2026-05-06T12:16:38.452Z",
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},
"title": "Apache::Session::Generate::ModUniqueId versions from 1.54 through 1.94 for Perl session ids are insecure",
"descriptions": [
{
"lang": "en",
"value": "Apache::Session::Generate::ModUniqueId versions from 1.54 through 1.94 for Perl session ids are insecure.\n\nApache::Session::Generate::ModUniqueId (added in version 1.54) uses the value of the UNIQUE_ID environment variable for the session id. The UNIQUE_ID variable is set by the Apache mod_unique_id plugin, which generates unique ids for the request. The id is based on the IPv4 address, the process id, the epoch time, a 16-bit counter and a thread index, with no obfuscation.\n\nThe server IP is often available to the public, and if not available, can be guessed from previous session ids being issued. The process ids may also be guessed from previous session ids. The timestamp is easily guessed (and leaked in the HTTP Date response header).\n\nThe purpose of mod_unique_id is to assign a unique id to requests so that events can be correlated in different logs. The id is not designed, nor is it suitable for security purposes."
}
],
"affected": [
{
"vendor": "CHORNY",
"product": "Apache::Session::Generate::ModUniqueId",
"collectionURL": "https://cpan.org/modules",
"packageName": "Apache-Session",
"programFiles": [
"lib/Session/Generate/ModUniqueId.pm"
],
"programRoutines": [
{
"name": "Apache::Session::Generate::ModUniqueId::generate_id"
}
],
"repo": "http://github.com/chorny/Apache-Session",
"defaultStatus": "unaffected",
"versions": [
{
"version": "1.54",
"status": "affected",
"versionType": "custom",
"lessThanOrEqual": "1.94"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"lang": "en",
"description": "CWE-340 Generation of Predictable Numbers or Identifiers",
"cweId": "CWE-340",
"type": "CWE"
}
]
}
],
"references": [
{
"url": "https://httpd.apache.org/docs/current/mod/mod_unique_id.html",
"tags": [
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]
},
{
"url": "https://metacpan.org/pod/Apache::Session::Generate::Random"
}
],
"impacts": [
{
"capecId": "CAPEC-115",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-115 Authentication Bypass"
}
]
}
],
"solutions": [
{
"lang": "en",
"value": "In cases where the session id is used for authentication or provides access to restricted data, consider alternate solutions like Apache::Session::Generate::Random."
}
]
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{
"providerMetadata": {
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP",
"dateUpdated": "2026-05-06T14:08:06.739Z"
},
"title": "CISA ADP Vulnrichment",
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"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"availabilityImpact": "NONE",
"baseScore": 9.1,
"baseSeverity": "CRITICAL"
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"shortName": "CVE",
"dateUpdated": "2026-05-06T16:32:47.250Z"
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"title": "CVE Program Container",
"references": [
{
"url": "http://www.openwall.com/lists/oss-security/2026/05/06/6"
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},
{
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"datePublic": "2026-05-06T12:16:38.452Z",
"title": "Apache::Session::Generate::ModUniqueId: Perl: mod_unique_id: Apache HTTP Server: Apache::Session::Generate::ModUniqueId: Session ID predictability allows unauthorized access",
"descriptions": [
{
"lang": "en",
"value": "A flaw was found in Apache::Session::Generate::ModUniqueId, a Perl module designed to generate session identifiers. This module uses the Apache mod_unique_id plugin's UNIQUE_ID environment variable directly as a session ID. The UNIQUE_ID is constructed from easily guessable information, such as the server's IP address, process ID, and timestamp, without sufficient randomness or obfuscation. This predictability allows a remote attacker to potentially guess valid session IDs, which could lead to session hijacking and unauthorized access to user accounts or sensitive information."
}
],
"affected": [
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"vendor": "Red Hat",
"product": "Red Hat Hardened Images",
"collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
"packageName": "perl",
"cpes": [
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"defaultStatus": "unaffected"
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"problemTypes": [
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"descriptions": [
{
"lang": "en",
"description": "Predictable from Observable State",
"cweId": "CWE-341",
"type": "CWE"
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]
}
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"url": "https://access.redhat.com/security/cve/CVE-2026-5081",
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{
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2467174",
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"attackVector": "NETWORK",
"attackComplexity": "LOW",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
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"integrityImpact": "LOW",
"availabilityImpact": "NONE",
"baseScore": 8.2,
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}
],
"timeline": [
{
"time": "2026-05-06T13:08:16.703Z",
"lang": "en",
"value": "Reported to Red Hat."
},
{
"time": "2026-05-06T12:16:38.452Z",
"lang": "en",
"value": "Made public."
}
]
}
]
}
}