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CVE-2026-107845

Contao: Cross-site scripting in the comments bundle

No known exploitation. EPSS puts it in the 19th percentile. No fix published yet.

CVSS 3.19.3CriticalEPSS percentile19th0.3% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
No public exploit knownFixNone yetNo fix or workaround published

Published Updated Sources: CVE.org, NVD

NVD CVE.org

What to do

No fixed build or workaround is published yet. Limit exposure and watch for a patch.

  • ContaoAffected: >= 4.0.0, < 5.3.50Upgrade to: not statedAffected: >= 5.4.0-RC1, < 5.7.12Upgrade to: not statedStated by: CVE record

Versions as the sources state them. Full version matrix after sign-in

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

Contao is an Open Source CMS. From version 4.0.0 until 5.3.50 and 5.7.12, an unauthenticated visitor can submit a comment whose email or website metadata is rendered without sufficient attribute and URL encoding by listComments() in comments-bundle/contao/dca/tl_comments.php. When a backend user opens the Comments module, attacker-controlled script can execute in the Contao backend origin under that user's session. Unpublished comments remain visible to moderators, so moderation does not prevent exposure. This issue is fixed in versions 5.3.50 and 5.7.12.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS19th
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

0.3% chance of exploitation activity in the next 30 days, which ranks it in the 19th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

7 events over 48 days, from the signal feeds we watch.

  1. Record updated
  2. Publishedweakness classified, att&ck mapped, record updated, record updated
  3. OpenVAS check added

Affected products

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

Scored 9.3 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required NoneNo authentication required — anyone can exploit this
  • User Interaction RequiredA user must click a link, open a file, or perform some action

Scope

  • Scope ChangedThe exploit can affect other components (e.g. sandbox escape, host compromise from VM)

Impact if exploited

  • Confidentiality HighTotal information disclosure — all data in the component is compromised
  • Integrity HighTotal loss of integrity — attacker can modify any data in the component
  • Availability NoneNo availability impact

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

And 1 more reference. See all after sign-in

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We'll flag the next CVE, public exploit or patch for Contao, not every advisory.