CVE-2026-42137: Kirby is an open-source content management system

Routine

MEDIUM 6.5UPGRADE

CVE-2026-42137 is a medium-severity flaw (CVSS 6.5) affecting kirby. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Kirby is an open-source content management system. Prior to versions 4.9.0 and 5.4.0, `pages.access/list` and `files.access/list` permissions are not consistently checked in the Panel and REST API. This issue has been patched in versions 4.9.0 and 5.4.0.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 77%)
CISA exploited list	No
Weakness	CWE-862, CWE-863
Published	2026-05-09
Last modified	2026-07-24

Publisher (CNA): GitHub, Inc. · Vendor: getkirby

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-09 04:16 UTCPublished CVE record published
2026-07-24 19:10 UTCUpdated Record last modified

getkirby kirby UPGRADE

Affected: < 4.9.0 · >= 5.0.0 and < 5.4.0

Fixed in: 4.9.0, 5.4.0

Safe to downgrade to: a release before 5.0.0

1. Check installed version

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

2. UPGRADE to 4.9.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade kirby

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 5.0.0 (Debian / Ubuntu)

apt-cache madison kirby sudo apt install kirby=<VERSION_BEFORE_5.0.0> sudo apt-mark hold kirby

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

dnf --showduplicates list kirby sudo dnf downgrade kirby-<VERSION_BEFORE_5.0.0> sudo dnf versionlock add kirby

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-2026-42137?

kirby: upgrade to 4.9.0, 5.4.0. Exact commands for each OS are on this page.

Is CVE-2026-42137 being exploited?

CVE-2026-42137 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-2026-42137 affect?

CVE-2026-42137 affects kirby. Severity is medium (CVSS 6.5). Kirby is an open-source content management system. Prior to versions 4.9.0 and 5.4.0, `pages.access/list` and `files.access/list` permissions are not consistently checked in the Panel and REST API. This issue has been patched in versions 4.

How urgent is CVE-2026-42137?

Priority 28/100. No elevated risk signals yet.

Related CVEs

CVE-2026-32870 HIGH 7.5 UPGRADE Kirby is an open-source content management system
CVE-2026-41325 HIGH 8.8 UPGRADE Kirby is an open-source content management system
CVE-2026-40099 MEDIUM 6.5 UPGRADE Kirby is an open-source content management system
CVE-2026-34587 HIGH 8.1 UPGRADE Kirby is an open-source content management system
CVE-2026-42069 MEDIUM 6.5 UPGRADE Kirby is an open-source content management system

References

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