Apache::Session::Generate::ModUniqueId versions from 1.54 through 1.94 for Perl session ids are insecure

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Summary

CVECVE-2026-5081
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-06 13:16:09 UTC
Updated2026-05-07 14:52:27 UTC
DescriptionApache::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.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS: 0.000380000 probability, percentile 0.114770000 (date 2026-05-12)

Problem Types: CWE-340 | CWE-340 CWE-340 Generation of Predictable Numbers or Identifiers

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA CHORNY ApacheSessionGenerateModUniqueId affected 1.54 1.94 custom Not specified

References

ReferenceSourceLinkTags
httpd.apache.org/docs/current/mod/mod_unique_id.html 9b29abf9-4ab0-4765-b253-1875cd9b441e httpd.apache.org
metacpan.org/pod/Apache::Session::Generate::Random 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
www.openwall.com/lists/oss-security/2026/05/06/6 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

Solutions

CNA: 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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