CVE-2026-5081

CriticalUpdated

Published: 06 May 2026

Published

06 May 2026

Modified

30 June 2026

KEV Added

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Patch

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CVSS Score v3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS Score 0.0030 21.9th percentile

Risk Priority 70 floored blend · peak EPSS

Summary

CVE-2026-5081 is a critical-severity Generation of Predictable Numbers or Identifiers (CWE-340) vulnerability in Chorny Apache\. Its CVSS base score is 9.1 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 21.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2026-27823

Vulnerability details

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.

CWE(s): CWE-340 CWE-341

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1550.004 Web Session Cookie Lateral Movement

Adversaries can use stolen session cookies to authenticate to web applications and services.

attack.mitre.org →

Why these techniques?

Predictable session IDs from observable state (CWE-340) in public-facing Apache/Perl module directly enables exploitation of the web app (T1190) and use of guessed/predicted web session cookies for impersonation (T1550.004).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0