CVE-2024-28234Network attack vector

CSS injection via unvalidated BBCode color value

Published Apr 9, 2024 · Updated Aug 2, 2024

CSS injection in Contao 2.0.0 through 4.13.39 and 5.0.0 through 5.3.3 allows remote attackers to alter page styling via comments. The comments-bundle parseBbCode method inserts an unvalidated color attribute directly into a span style declaration. BBCode must be enabled, and a visitor must view the rendered comment for attacker-controlled CSS to affect the page.

CVSS severity4.3
Medium
EPSS probability0.57%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CSS injection in Contao 2.0.0 through 4.13.39 and 5.0.0 through 5.3.3 allows remote attackers to alter page styling via comments. The comments-bundle parseBbCode method inserts an unvalidated color attribute directly into a span style declaration. BBCode must be enabled, and a visitor must view the rendered comment for attacker-controlled CSS to affect the page.

The record

CVE
CVE-2024-28234
Published
Apr 9, 2024
Updated
Aug 2, 2024
Vendor
Contao
Product
Contao
Classifications
CWE-74
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 9, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 2.0.0, < 4.13.40
  2. Affected versionversion=>= 5.0.0, < 5.3.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Contao · Contaoversion=>= 2.0.0, < 4.13.40; version=>= 5.0.0, < 5.3.4

Published CVSS scores

4.7NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
4.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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