dbcve.org
Apache\Web server / proxy · Chorny

CVE-2026-5081

CRITICAL · 9.1 CVSS v3.1 Published 2026-05-06
Fix available
A fix is available. Upgrade to after 1.94 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Apache::Session::Generate::ModUniqueId versions 1.54-1.94 use Apache's mod_unique_id environment variable for session ID generation. This ID is based on predictable components (server IPv4 address, process ID, epoch time, counter, thread index) that can all be derived or guessed from public information or previously issued session IDs, allowing attackers to predict and hijack valid sessions.

MitigationReplace Apache::Session::Generate::ModUniqueId with a cryptographically secure session ID generator (such as Apache::Session::Generate::MD5 or ::SHA) that uses random data, and invalidate existing sessions upon migration.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Apache\Web server / proxy
Affected:>= 1.54, <= 1.94

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed version of Apache::Session::Generate::ModUniqueId
    Run: perl -MApache::Session::Generate::ModUniqueId -e 'print $Apache::Session::Generate::ModUniqueId::VERSION'
    Affected if The version returned is >= 1.54 and <= 1.94
  2. Verify session generation module in use
    Search your application code and session configuration files for 'Apache::Session::Generate::ModUniqueId' or 'ModUniqueId' in session generation directives
    Affected if The code explicitly loads or configures Apache::Session::Generate::ModUniqueId for session ID generation
  3. Check if Apache mod_unique_id is enabled
    Run: apache2ctl -M 2>/dev/null | grep unique_id OR httpd -M 2>/dev/null | grep unique_id
    Affected if mod_unique_id is loaded in the Apache instance serving the application
  4. Inspect generated session IDs for predictability
    Generate multiple session IDs via your application and examine their format. ModUniqueId IDs typically contain hex-encoded components based on IP, PID, timestamp, and counters
    Affected if Session IDs appear to contain structured hex patterns that could reveal the components described in the CVE (IPv4, PID, timestamp, counter, thread index)
  5. Review Perl application dependencies
    Examine your application's Makefile.PL, Build.PL, or cpanfile for a dependency on Apache::Session::Generate::ModUniqueId within the 1.54-1.94 range
    Affected if The application declares a dependency on a vulnerable version of this module

Your environment is affected if you are using Apache::Session::Generate::ModUniqueId version 1.54 through 1.94 with mod_unique_id enabled, and your application relies on this module for session ID generation.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 1.94
Interim mitigation

Replace Apache::Session::Generate::ModUniqueId with a cryptographically secure session ID generator (such as Apache::Session::Generate::MD5 or ::SHA) that uses random data, and invalidate existing sessions upon migration.

Recommended fix Moderate confidence

Version > 1.94 (latest available version on CPAN)

  1. 1. Identify the current version of Apache::Session::Generate::ModUniqueId installed in your Perl environment by running: cpan -D Apache::Session::Generate::ModUniqueId
  2. 2. Upgrade to a version greater than 1.94 using cpan or cpanm: cpan -T Apache::Session::Generate::ModUniqueId or cpanm Apache::Session::Generate::ModUniqueId
  3. 3. Verify the upgrade was successful by checking the new version: cpan -D Apache::Session::Generate::ModUniqueId
  4. 4. Test your application to ensure session functionality works correctly with the updated module
  5. 5. Consider migrating to a more secure session ID generation mechanism if available (such as Apache::Session::Generate::MD5 or Apache::Session::Generate::Random)
Caveat Review release notes for any API changes between 1.94 and the new version; test thoroughly before deploying to production

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Apache\ Scoped from the published advisory
  • Consultation4.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA3.0 h
25.0 hours of engineering $4,400
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-5081 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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