CVE-2026-5774: Improper synchronization of the userTokens map in the API server in Canonical Juju 4.0.5, 3.6.20, and 2.9.56 m

Routine

MEDIUM 6.4UPGRADE

CVE-2026-5774 is a medium-severity flaw (CVSS 6.4) affecting juju. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper synchronization of the userTokens map in the API server in Canonical Juju 4.0.5, 3.6.20, and 2.9.56 may allow an authenticated user to possibly cause a denial of service on the server or possibly reuse a single-use discharge token.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.4 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 85%)
CISA exploited list	No
Weakness	CWE-362
Published	2026-04-10
Last modified	2026-10-26

Publisher (CNA): Canonical Ltd. · Vendor: canonical

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-10 13:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

canonical juju UPGRADE

Affected: < 2.9.57 · >= 3.0 and < 3.6.21 · >= 4.0 and < 4.0.6

Fixed in: 2.9.57, 3.6.21, 4.0.6

Safe to downgrade to: a release before 3.0

1. Check installed version

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

2. UPGRADE to 2.9.57 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade juju

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 3.0 (Debian / Ubuntu)

apt-cache madison juju sudo apt install juju=<VERSION_BEFORE_3.0> sudo apt-mark hold juju

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

dnf --showduplicates list juju sudo dnf downgrade juju-<VERSION_BEFORE_3.0> sudo dnf versionlock add juju

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-2026-5774?

juju: upgrade to 2.9.57, 3.6.21, 4.0.6. Exact commands for each OS are on this page.

Is CVE-2026-5774 being exploited?

CVE-2026-5774 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-2026-5774 affect?

CVE-2026-5774 affects juju. Severity is medium (CVSS 6.4). Improper synchronization of the userTokens map in the API server in Canonical Juju 4.0.5, 3.6.20, and 2.9.56 may allow an authenticated user to possibly cause a denial of service on the server or possibly reuse a single-use discharge token.

How urgent is CVE-2026-5774?

Priority 31/100. Public exploit reference

Related CVEs

CVE-2026-4370 CRITICAL 10.0 UPGRADE A vulnerability was identified in Juju from version 3.2.0 until 3.6.19 and from version 4.0 until 4.0.4, where
CVE-2026-5412 CRITICAL 9.9 UPGRADE In Juju versions prior to 2.9.57 and 3.6.21, an authorization issue exists in the Controller facade

References

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