CVE-2024-28234: Contao is an open source content management system

Routine

MEDIUM 4.3UPGRADE

CVE-2024-28234 is a medium-severity flaw (CVSS 4.3) affecting contao. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Contao is an open source content management system. Starting in version 2.0.0 and prior to versions 4.13.40 and 5.3.4, it is possible to inject CSS styles via BBCode in comments. Installations are only affected if BBCode is enabled. Contao versions 4.13.40 and 5.3.4 have a patch for this issue. As a workaround, disable BBCode for comments.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.6% (top 53%)
CISA exploited list	No
Weakness	CWE-74
Published	2024-04-09
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2024-04-09 14:15 UTCPublished CVE record published
2026-06-17 07:21 UTCUpdated Record last modified

contao contao UPGRADE

Affected: >= 2.0 and < 4.13.40 · >= 5.0.0 and < 5.3.4

Fixed in: 4.13.40, 5.3.4

Safe to downgrade to: a release before 2.0

1. Check installed version

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

2. UPGRADE to 4.13.40 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade contao

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 2.0 (Debian / Ubuntu)

apt-cache madison contao sudo apt install contao=<VERSION_BEFORE_2.0> sudo apt-mark hold contao

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

dnf --showduplicates list contao sudo dnf downgrade contao-<VERSION_BEFORE_2.0> sudo dnf versionlock add contao

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-2024-28234?

contao: upgrade to 4.13.40, 5.3.4. Exact commands for each OS are on this page.

Is CVE-2024-28234 being exploited?

CVE-2024-28234 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-2024-28234 affect?

CVE-2024-28234 affects contao. Severity is medium (CVSS 4.3). Contao is an open source content management system. Starting in version 2.0.0 and prior to versions 4.13.40 and 5.3.4, it is possible to inject CSS styles via BBCode in comments. Installations are only affected if BBCode is enabled. Contao

How urgent is CVE-2024-28234?

Priority 27/100. No elevated risk signals yet.

Related CVEs

CVE-2025-65960 MEDIUM 6.6 UPGRADE Contao is an Open Source CMS
CVE-2025-65961 LOW 3.3 UPGRADE Contao is an Open Source CMS
CVE-2025-57759 MEDIUM 4.3 UPGRADE Contao is an Open Source CMS
CVE-2025-57758 MEDIUM 4.3 UPGRADE Contao is an Open Source CMS
CVE-2025-57757 MEDIUM 5.3 UPGRADE Contao is an Open Source CMS

References

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