SimpleSAMLphp has a logging functionality that allows system administrators to keep track of the activity, errors, and statistics. Additionally, it allows users to report errors, shall they happen. An error report contains a report identifier, which is logged once submitted.
www/errorreport.php script, which receives error reports and sends them via email to the system administrator,
didn’t properly sanitize the report identifier obtained from the request. This allows an attacker, under specific
circumstances, to inject new log lines by manually crafting this report ID.
When configured to use the
file logging handler, SimpleSAMLphp will output all its logs by appending each log line to
a given file. Since the
reportID parameter received in a request sent to
www/errorreport.php was not properly
sanitized, it was possible to inject newline characters into it, effectively allowing a malicious user to inject new
log lines with arbitrary content.
SimpleSAMLphp versions up to 1.18.3.
An attacker may use this issue to inject logs messages into a SimpleSAMLphp log file, trying to trick or confuse system
administrators. However, the attack surface is considered small, as the attack will only work with the
handler, which opens the log file in append-only mode. This means an attacker cannot edit or remove existing log
messages, and even if non-ascii characters are written to the log, the file will always be readable with a simple text
Upgrade the SimpleSAMLphp installation to version 1.18.4.
This vulnerability was discovered and reported by Frederic Vleminckx on January 23, 2020.