CVE-2026-2439: Concierge::Sessions versions from 0.8.1 before 0.8.5 for Perl generate insecure session ids

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CRITICAL 9.8REMOTEUPGRADE

CVE-2026-2439 is a critical-severity flaw (CVSS 9.8) affecting concierge\. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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. T

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 60%)
CISA exploited list	No
Weakness	CWE-338, CWE-340
Published	2026-02-16
Last modified	2026-06-17

Publisher (CNA): CPANSec · Vendor: bva

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-02-16 22:22 UTCPublished CVE record published
2026-06-17 10:30 UTCUpdated Record last modified

bva concierge\ UPGRADE

Affected: >= 0.8.1 and < 0.8.5

Fixed in: 0.8.5

Safe to downgrade to: a release before 0.8.1

1. Check installed version

apt-cache policy concierge || rpm -q concierge || concierge --version

2. UPGRADE to 0.8.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade concierge

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade concierge

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 0.8.1 (Debian / Ubuntu)

apt-cache madison concierge sudo apt install concierge=<VERSION_BEFORE_0.8.1> sudo apt-mark hold concierge

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list concierge sudo dnf downgrade concierge-<VERSION_BEFORE_0.8.1> sudo dnf versionlock add concierge

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-2439?

concierge\: upgrade to 0.8.5. Exact commands for each OS are on this page.

Is CVE-2026-2439 being exploited?

CVE-2026-2439 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-2439 affect?

CVE-2026-2439 affects concierge\. Severity is critical (CVSS 9.8). 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 Pe

How urgent is CVE-2026-2439?

Priority 49/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

Perl vulnerabilities

References

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