dbcve.org
Concierge\Application · Bva

CVE-2026-2439

CRITICAL · 9.8 CVSS v3.1 Published 2026-02-16
Fix available
A fix is available. Upgrade to 0.8.5 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

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
Concierge::Sessions versions from 0.8.1 before 0.8.5 for Perl generate insecure session ids. The generate_session_id function in Concierge::Sessions::Base defaults to using the uuidgen command to generate a UUID, with a fallback to using Perl's built-in rand function. Neither of these methods are secure, and attackers are able to guess session_ids that can grant them access to systems. Specifically, * There is no warning when uuidgen fails. The software can be quietly using the fallback rand() function with no warnings if the command fails for any reason. * The uuidgen command will generate a time-based UUID if the system does not have a high-quality random number source, because the call does not explicitly specify the --random option. Note that the system time is shared in HTTP responses. * UUIDs are identifiers whose mere possession grants access, as per RFC 9562. * The output of the built-in rand() function is predictable and unsuitable for security applications.

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

Concierge::Sessions versions 0.8.1-0.8.4 generate insecure session IDs using the uuidgen command without the --random option (producing predictable time-based UUIDs) and a fallback to Perl's weak rand() function. Session IDs grant access simply by possession, making predictable IDs trivially exploitable for session hijacking.

MitigationUpgrade to Concierge::Sessions version 0.8.5 or later which implements cryptographically secure session ID generation; alternatively, ensure uuidgen is called with --random and replace rand() with a CSPRNG.

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
Concierge\Application
Affected:>= 0.8.1, < 0.8.5

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
High

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

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 Concierge::Sessions version
    Run 'perldoc Concierge::Sessions' or check the installed module version using 'perl -MConcierge::Sessions -e 'print $Concierge::Sessions::VERSION''
    Affected if The installed version is 0.8.1, 0.8.2, 0.8.3, or 0.8.4
  2. Verify uuidgen invocation in source code
    Inspect the Concierge::Sessions Perl module file (typically in site_lib or perllocal) and locate the uuidgen command execution. Search for 'uuidgen' without the '--random' flag
    Affected if uuidgen is called without the --random option, producing time-based predictable UUIDs
  3. Check for weak rand() fallback
    Locate the session ID generation routine in the module source and verify if Perl's rand() function is used as a fallback mechanism
    Affected if The code contains a fallback to rand() for session ID generation
  4. Determine session ID predictability
    Generate multiple session IDs and analyze them. If they follow a sequential or time-based pattern, they are predictable. Use a test script to call the session creation function multiple times and observe the ID format
    Affected if Session IDs exhibit predictable patterns based on timestamps or sequential values rather than cryptographically random data

If Concierge::Sessions version 0.8.1-0.8.4 is installed and the module generates session IDs via uuidgen without --random or uses the rand() fallback, the environment is vulnerable to session hijacking due to predictable session IDs.

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 0.8.5 or later
Fixed in 0.8.5
Vendor patch github.com →
Interim mitigation

Upgrade to Concierge::Sessions version 0.8.5 or later which implements cryptographically secure session ID generation; alternatively, ensure uuidgen is called with --random and replace rand() with a CSPRNG.

Recommended fix High confidence

Concierge::Sessions version 0.8.5

  1. 1. Identify the current version of Concierge::Sessions installed in your Perl environment using 'cpan -D Concierge::Sessions' or by checking your dependency file
  2. 2. If the installed version is >= 0.8.1 and < 0.8.5, upgrade to version 0.8.5 or later using 'cpan Concierge::Sessions' or 'cpanm Concierge::Sessions'
  3. 3. Verify the upgrade was successful by checking the installed version again
  4. 4. After upgrading, test that session creation functions correctly and session IDs are being generated using a cryptographically secure method (such as with the --random flag for uuidgen or a proper CSPRNG)

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

Fix this in Concierge\ Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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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-2026-2439 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
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  • Version or environment caveats, and links to real fixes
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