Security advisories

Here you will find a list of vulnerabilities that have already been found and fixed in Contao. If you think that you have found a security issue in Contao, please report it according to our security policy.

Cross site scripting in the system log

by Leo Feyer

Date: 2021-06-23
CVE ID: CVE-2021-35210


It is possible to inject code into the tl_log table that will be executed in the browser when the system log is called in the back end. The attacker does not have to be logged in.

Affected versions

Contao 4.5
Contao 4.6
Contao 4.7
Contao 4.8
Contao 4.9 up to 4.9.15
Contao 4.10
Contao 4.11 up to 4.11.4

Suggested solution

Update to Contao 4.9.16 or 4.11.5.


Disable the system log module in the back end for all users (especially admin users).

More information

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